diff --git a/1-js/02-first-steps/04-variables/article.md b/1-js/02-first-steps/04-variables/article.md
index 0b2e74715..2d7e49233 100644
--- a/1-js/02-first-steps/04-variables/article.md
+++ b/1-js/02-first-steps/04-variables/article.md
@@ -194,7 +194,11 @@ let my-name; // παύλες '-' απαγορεύονται
 ```
 
 ```smart header="Case matters"
+<<<<<<< HEAD
 Μεταβλητές `apple` και `AppLE` είναι δύο διαφορετικές μεταβλητές.
+=======
+Variables named `apple` and `APPLE` are two different variables.
+>>>>>>> 206485fc3a5465f961608b6e7303fae2e1a0e0b5
 ```
 
 ````smart header="Non-Latin letters are allowed, but not recommended"
@@ -298,7 +302,11 @@ const pageLoadTime = /* ο χρόνος που χρειάζεται για να
 
 Η τιμή του "pageLoadTime" δεν είναι γνωστή πριν από τη φόρτωση της σελίδας, επομένως έχει κανονική ονομασία. Αλλά εξακολουθεί να είναι σταθερή επειδή δεν αλλάζει μετά την ανάθεση.
 
+<<<<<<< HEAD
 Με άλλα λόγια, οι σταθερές με κεφαλαία ονομασία χρησιμοποιούνται μόνο ως ψευδώνυμα για  "hard-coded" τιμές.  
+=======
+In other words, capital-named constants are only used as aliases for "hard-coded" values.
+>>>>>>> 206485fc3a5465f961608b6e7303fae2e1a0e0b5
 
 ## Να λεμε τα πράγματα με το ονομά τους 
 
diff --git a/1-js/02-first-steps/13-while-for/article.md b/1-js/02-first-steps/13-while-for/article.md
index a8c9d3ad2..612cec770 100644
--- a/1-js/02-first-steps/13-while-for/article.md
+++ b/1-js/02-first-steps/13-while-for/article.md
@@ -263,7 +263,11 @@ for (let i = 0; i < 10; i++) {
 
 Από τεχνική άποψη, αυτό είναι πανομοιότυπο με το παραπάνω παράδειγμα. Σίγουρα, μπορούμε απλώς να τυλίξουμε τον κώδικα σε ένα μπλοκ `if` αντί να χρησιμοποιήσουμε το `continue`.
 
+<<<<<<< HEAD
 Αλλά ως παρενέργεια, αυτό δημιούργησε ένα ακόμη επίπεδο ένθεσης (η κλήση `alert` μέσα στα άγκυστρα). Εάν ο κώδικας στο εσωτερικό του `if` είναι μεγαλύτερος από μερικές γραμμές, αυτό μπορεί να μειώσει τη συνολική αναγνωσιμότητα.
+=======
+But as a side effect, this created one more level of nesting (the `alert` call inside the curly braces). If the code inside of `if` is longer than a few lines, that may decrease the overall readability.
+>>>>>>> 206485fc3a5465f961608b6e7303fae2e1a0e0b5
 ````
 
 ````warn header="Δεν υπάρχει `break/continue` στη δεξιά πλευρά του '?'"
diff --git a/1-js/02-first-steps/14-switch/article.md b/1-js/02-first-steps/14-switch/article.md
index f33d062a4..11f52109f 100644
--- a/1-js/02-first-steps/14-switch/article.md
+++ b/1-js/02-first-steps/14-switch/article.md
@@ -139,7 +139,11 @@ switch (a) {
 
 Τώρα και τα δύο `3` και `5` εμφανίζουν το ίδιο μήνυμα.
 
+<<<<<<< HEAD
 Η ικανότητα "ομαδοποίησης" περιπτώσεων είναι μια παρενέργεια του τρόπου λειτουργίας του `switch/case` χωρίς το `break`. Εδώ η εκτέλεση του `case 3` ξεκινά από τη γραμμή `(*)` και περνάει από το `case 5`, επειδή δεν υπάρχει `break`.
+=======
+The ability to "group" cases is a side effect of how `switch/case` works without `break`. Here the execution of `case 3` starts from the line `(*)` and goes through `case 5`, because there's no `break`.
+>>>>>>> 206485fc3a5465f961608b6e7303fae2e1a0e0b5
 
 ## Η σημασία του τύπου
 
diff --git a/1-js/02-first-steps/15-function-basics/article.md b/1-js/02-first-steps/15-function-basics/article.md
index 92ff31d0d..ab4c9930b 100644
--- a/1-js/02-first-steps/15-function-basics/article.md
+++ b/1-js/02-first-steps/15-function-basics/article.md
@@ -470,7 +470,11 @@ function name(parameters, delimited, by, comma) {
 
 Για να κάνετε τον κώδικα καθαρό και κατανοητό, συνίσταται η χρήση κυρίως τοπικών μεταβλητών και παραμέτρων στη συνάρτηση, όχι εξωτερικών μεταβλητών.
 
+<<<<<<< HEAD
 Είναι πάντα πιο εύκολο να κατανοήσουμε μια συνάρτηση που παίρνει παραμέτρους, δουλεύει μαζί τους και επιστρέφει ένα αποτέλεσμα, παρά μια συνάρτηση που δεν έχει παραμέτρους, αλλά τροποποιεί τις εξωτερικές μεταβλητές ως side-effect.
+=======
+It is always easier to understand a function which gets parameters, works with them and returns a result than a function which gets no parameters, but modifies outer variables as a side effect.
+>>>>>>> 206485fc3a5465f961608b6e7303fae2e1a0e0b5
 
 Ονομασία συναρτήσεων:
 
diff --git a/1-js/02-first-steps/16-function-expressions/article.md b/1-js/02-first-steps/16-function-expressions/article.md
index 0135cf1cb..d502c9d27 100644
--- a/1-js/02-first-steps/16-function-expressions/article.md
+++ b/1-js/02-first-steps/16-function-expressions/article.md
@@ -90,7 +90,7 @@ Everything would work the same.
 
 
 ````smart header="Why is there a semicolon at the end?"
-You might wonder, why does Function Expression have a semicolon `;` at the end, but Function Declaration does not:
+You might wonder, why do Function Expressions have a semicolon `;` at the end, but Function Declarations do not:
 
 ```js
 function sayHi() {
@@ -144,13 +144,13 @@ function showCancel() {
 ask("Do you agree?", showOk, showCancel);
 ```
 
-In practice, such functions are quite useful. The major difference between a real-life `ask` and the example above is that real-life functions use more complex ways to interact with the user than a simple `confirm`. In the browser, such function usually draws a nice-looking question window. But that's another story.
+In practice, such functions are quite useful. The major difference between a real-life `ask` and the example above is that real-life functions use more complex ways to interact with the user than a simple `confirm`. In the browser, such functions usually draw a nice-looking question window. But that's another story.
 
 **The arguments `showOk` and `showCancel` of `ask` are called *callback functions* or just *callbacks*.**
 
 The idea is that we pass a function and expect it to be "called back" later if necessary. In our case, `showOk` becomes the callback for "yes" answer, and `showCancel` for "no" answer.
 
-We can use Function Expressions to write the same function much shorter:
+We can use Function Expressions to write an equivalent, shorter function:
 
 ```js run no-beautify
 function ask(question, yes, no) {
@@ -186,7 +186,7 @@ Let's formulate the key differences between Function Declarations and Expression
 
 First, the syntax: how to differentiate between them in the code.
 
-- *Function Declaration:* a function, declared as a separate statement, in the main code flow.
+- *Function Declaration:* a function, declared as a separate statement, in the main code flow:
 
     ```js
     // Function Declaration
diff --git a/1-js/03-code-quality/05-testing-mocha/article.md b/1-js/03-code-quality/05-testing-mocha/article.md
index 9037b484d..79f190370 100644
--- a/1-js/03-code-quality/05-testing-mocha/article.md
+++ b/1-js/03-code-quality/05-testing-mocha/article.md
@@ -51,7 +51,7 @@ describe("pow", function() {
 A spec has three main building blocks that you can see above:
 
 `describe("title", function() { ... })`
-: What functionality we're describing. In our case we're describing the function `pow`. Used to group "workers" -- the `it` blocks.
+: What functionality we're describing? In our case we're describing the function `pow`. Used to group "workers" -- the `it` blocks.
 
 `it("use case description", function() { ... })`
 : In the title of `it` we *in a human-readable way* describe the particular use case, and the second argument is a function that tests it.
diff --git a/1-js/04-object-basics/02-object-copy/article.md b/1-js/04-object-basics/02-object-copy/article.md
index b56a8034b..7fe8a26a6 100644
--- a/1-js/04-object-basics/02-object-copy/article.md
+++ b/1-js/04-object-basics/02-object-copy/article.md
@@ -37,7 +37,7 @@ And here's how it's actually stored in memory:
 
 The object is stored somewhere in memory (at the right of the picture), while the `user` variable (at the left) has a "reference" to it.
 
-We may think of an object variable, such as `user`, as like a sheet of paper with the address of the object on it.
+We may think of an object variable, such as `user`, like a sheet of paper with the address of the object on it.
 
 When we perform actions with the object, e.g. take a property `user.name`, the JavaScript engine looks at what's at that address and performs the operation on the actual object.
 
@@ -104,11 +104,9 @@ For comparisons like `obj1 > obj2` or for a comparison against a primitive `obj
 
 So, copying an object variable creates one more reference to the same object.
 
-But what if we need to duplicate an object? Create an independent copy, a clone?
+But what if we need to duplicate an object?
 
-That's also doable, but a little bit more difficult, because there's no built-in method for that in JavaScript. But there is rarely a need -- copying by reference is good most of the time.
-
-But if we really want that, then we need to create a new object and replicate the structure of the existing one by iterating over its properties and copying them on the primitive level.
+We can create a new object and replicate the structure of the existing one, by iterating over its properties and copying them on the primitive level.
 
 Like this:
 
@@ -133,7 +131,7 @@ clone.name = "Pete"; // changed the data in it
 alert( user.name ); // still John in the original object
 ```
 
-Also we can use the method [Object.assign](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign) for that.
+We can also use the method [Object.assign](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign).
 
 The syntax is:
 
@@ -190,7 +188,7 @@ There are also other methods of cloning an object, e.g. using the [spread syntax
 
 ## Nested cloning
 
-Until now we assumed that all properties of `user` are primitive. But properties can be references to other objects. What to do with them?
+Until now we assumed that all properties of `user` are primitive. But properties can be references to other objects.
 
 Like this:
 ```js run
@@ -205,9 +203,7 @@ let user = {
 alert( user.sizes.height ); // 182
 ```
 
-Now it's not enough to copy `clone.sizes = user.sizes`, because the `user.sizes` is an object, it will be copied by reference. So `clone` and `user` will share the same sizes:
-
-Like this:
+Now it's not enough to copy `clone.sizes = user.sizes`, because `user.sizes` is an object, and will be copied by reference, so `clone` and `user` will share the same sizes:
 
 ```js run
 let user = {
@@ -224,10 +220,10 @@ alert( user.sizes === clone.sizes ); // true, same object
 
 // user and clone share sizes
 user.sizes.width++;       // change a property from one place
-alert(clone.sizes.width); // 51, see the result from the other one
+alert(clone.sizes.width); // 51, get the result from the other one
 ```
 
-To fix that, we should use a cloning loop that examines each value of `user[key]` and, if it's an object, then replicate its structure as well. That is called a "deep cloning".
+To fix that and make `user` and `clone` truly separate objects, we should use a cloning loop that examines each value of `user[key]` and, if it's an object, then replicate its structure as well. That is called a "deep cloning".
 
 We can use recursion to implement it. Or, to not reinvent the wheel, take an existing implementation, for instance [_.cloneDeep(obj)](https://lodash.com/docs#cloneDeep) from the JavaScript library [lodash](https://lodash.com).
 
diff --git a/1-js/04-object-basics/08-symbol/article.md b/1-js/04-object-basics/08-symbol/article.md
index f61e88583..d6b8e9c9b 100644
--- a/1-js/04-object-basics/08-symbol/article.md
+++ b/1-js/04-object-basics/08-symbol/article.md
@@ -238,7 +238,7 @@ alert( Symbol.keyFor(sym2) ); // id
 
 The `Symbol.keyFor` internally uses the global symbol registry to look up the key for the symbol. So it doesn't work for non-global symbols. If the symbol is not global, it won't be able to find it and returns `undefined`.
 
-That said, any symbols have `description` property.
+That said, all symbols have the `description` property.
 
 For instance:
 
diff --git a/1-js/05-data-types/01-primitives-methods/1-string-new-property/task.md b/1-js/05-data-types/01-primitives-methods/1-string-new-property/task.md
index 50c781ea5..208f84cc7 100644
--- a/1-js/05-data-types/01-primitives-methods/1-string-new-property/task.md
+++ b/1-js/05-data-types/01-primitives-methods/1-string-new-property/task.md
@@ -15,4 +15,4 @@ str.test = 5;
 alert(str.test);
 ```
 
-How do you think, will it work? What will be shown?
+What do you think, will it work? What will be shown?
diff --git a/1-js/05-data-types/02-number/article.md b/1-js/05-data-types/02-number/article.md
index afb679890..0e7c8b6c8 100644
--- a/1-js/05-data-types/02-number/article.md
+++ b/1-js/05-data-types/02-number/article.md
@@ -178,7 +178,7 @@ There are two ways to do so:
     alert( num.toFixed(1) ); // "12.4"
     ```
 
-    Please note that result of `toFixed` is a string. If the decimal part is shorter than required, zeroes are appended to the end:
+    Please note that the result of `toFixed` is a string. If the decimal part is shorter than required, zeroes are appended to the end:
 
     ```js run
     let num = 12.34;
@@ -246,7 +246,7 @@ Can we work around the problem? Sure, the most reliable method is to round the r
 
 ```js run
 let sum = 0.1 + 0.2;
-alert( sum.toFixed(2) ); // 0.30
+alert( sum.toFixed(2) ); // "0.30"
 ```
 
 Please note that `toFixed` always returns a string. It ensures that it has 2 digits after the decimal point. That's actually convenient if we have an e-shopping and need to show `$0.30`. For other cases, we can use the unary plus to coerce it into a number:
diff --git a/1-js/05-data-types/03-string/article.md b/1-js/05-data-types/03-string/article.md
index 41bda2254..b3535866d 100644
--- a/1-js/05-data-types/03-string/article.md
+++ b/1-js/05-data-types/03-string/article.md
@@ -48,7 +48,7 @@ let guestList = "Guests: // Error: Unexpected token ILLEGAL
   * John";
 ```
 
-Single and double quotes come from ancient times of language creation when the need for multiline strings was not taken into account. Backticks appeared much later and thus are more versatile.
+Single and double quotes come from ancient times of language creation, when the need for multiline strings was not taken into account. Backticks appeared much later and thus are more versatile.
 
 Backticks also allow us to specify a "template function" before the first backtick. The syntax is: <code>func&#96;string&#96;</code>. The function `func` is called automatically, receives the string and embedded expressions and can process them. This is called "tagged templates". This feature makes it easier to implement custom templating, but is rarely used in practice. You can read more about it in the [manual](mdn:/JavaScript/Reference/Template_literals#Tagged_templates).
 
@@ -214,7 +214,7 @@ alert( 'Interface'.toLowerCase() ); // interface
 
 Or, if we want a single character lowercased:
 
-```js
+```js run
 alert( 'Interface'[0].toLowerCase() ); // 'i'
 ```
 
@@ -371,8 +371,8 @@ alert( "Widget".includes("id", 3) ); // false, from position 3 there is no "id"
 The methods [str.startsWith](mdn:js/String/startsWith) and [str.endsWith](mdn:js/String/endsWith) do exactly what they say:
 
 ```js run
-alert( "Widget".startsWith("Wid") ); // true, "Widget" starts with "Wid"
-alert( "Widget".endsWith("get") ); // true, "Widget" ends with "get"
+alert( "*!*Wid*/!*get".startsWith("Wid") ); // true, "Widget" starts with "Wid"
+alert( "Wid*!*get*/!*".endsWith("get") ); // true, "Widget" ends with "get"
 ```
 
 ## Getting a substring
@@ -604,7 +604,7 @@ You will find more ways to deal with surrogate pairs later in the chapter <info:
 
 ### Diacritical marks and normalization
 
-In many languages there are symbols that are composed of the base character with a mark above/under it.
+In many languages, there are symbols that are composed of the base character with a mark above/under it.
 
 For instance, the letter `a` can be the base character for: `àáâäãåā`. Most common "composite" character have their own code in the UTF-16 table. But not all of them, because there are too many possible combinations.
 
diff --git a/1-js/06-advanced-functions/06-function-object/article.md b/1-js/06-advanced-functions/06-function-object/article.md
index 12342f45a..c84f4e52f 100644
--- a/1-js/06-advanced-functions/06-function-object/article.md
+++ b/1-js/06-advanced-functions/06-function-object/article.md
@@ -326,7 +326,7 @@ welcome(); // Hello, Guest (nested call works)
 
 Now it works, because the name `"func"` is function-local. It is not taken from outside (and not visible there). The specification guarantees that it will always reference the current function.
 
-The outer code still has its variable `sayHi` or `welcome`. And `func` is an "internal function name", how the function can call itself internally.
+The outer code still has its variable `sayHi` or `welcome`. And `func` is an "internal function name", the way for the function to can call itself reliably.
 
 ```smart header="There's no such thing for Function Declaration"
 The "internal name" feature described here is only available for Function Expressions, not for Function Declarations. For Function Declarations, there is no syntax for adding an "internal" name.
diff --git a/1-js/06-advanced-functions/08-settimeout-setinterval/article.md b/1-js/06-advanced-functions/08-settimeout-setinterval/article.md
index 984102687..e4203f57e 100644
--- a/1-js/06-advanced-functions/08-settimeout-setinterval/article.md
+++ b/1-js/06-advanced-functions/08-settimeout-setinterval/article.md
@@ -232,7 +232,7 @@ setTimeout(function() {...}, 100);
 
 For `setInterval` the function stays in memory until `clearInterval` is called.
 
-There's a side-effect. A function references the outer lexical environment, so, while it lives, outer variables live too. They may take much more memory than the function itself. So when we don't need the scheduled function anymore, it's better to cancel it, even if it's very small.
+There's a side effect. A function references the outer lexical environment, so, while it lives, outer variables live too. They may take much more memory than the function itself. So when we don't need the scheduled function anymore, it's better to cancel it, even if it's very small.
 ````
 
 ## Zero delay setTimeout
diff --git a/1-js/08-prototypes/04-prototype-methods/2-dictionary-tostring/solution.md b/1-js/08-prototypes/04-prototype-methods/2-dictionary-tostring/solution.md
index a92e17900..f3c9cf0e5 100644
--- a/1-js/08-prototypes/04-prototype-methods/2-dictionary-tostring/solution.md
+++ b/1-js/08-prototypes/04-prototype-methods/2-dictionary-tostring/solution.md
@@ -28,4 +28,4 @@ alert(dictionary); // "apple,__proto__"
 
 When we create a property using a descriptor, its flags are `false` by default. So in the code above, `dictionary.toString` is non-enumerable.
 
-See the the chapter [](info:property-descriptors) for review.
+See the chapter [](info:property-descriptors) for review.
diff --git a/1-js/09-classes/03-static-properties-methods/3-class-extend-object/solution.md b/1-js/09-classes/03-static-properties-methods/3-class-extend-object/solution.md
index ca9e80601..cb9829ce0 100644
--- a/1-js/09-classes/03-static-properties-methods/3-class-extend-object/solution.md
+++ b/1-js/09-classes/03-static-properties-methods/3-class-extend-object/solution.md
@@ -21,14 +21,14 @@ alert( rabbit.hasOwnProperty('name') ); // true
 
 But that's not all yet.
 
-Even after the fix, there's still important difference in `"class Rabbit extends Object"` versus `class Rabbit`.
+Even after the fix, there's still an important difference between `"class Rabbit extends Object"` and `class Rabbit`.
 
 As we know, the "extends" syntax sets up two prototypes:
 
 1. Between `"prototype"` of the constructor functions (for methods).
 2. Between the constructor functions themselves (for static methods).
 
-In our case, for `class Rabbit extends Object` it means:
+In the case of `class Rabbit extends Object` it means:
 
 ```js run
 class Rabbit extends Object {}
@@ -37,7 +37,7 @@ alert( Rabbit.prototype.__proto__ === Object.prototype ); // (1) true
 alert( Rabbit.__proto__ === Object ); // (2) true
 ```
 
-So `Rabbit` now provides access to static methods of `Object` via `Rabbit`, like this:
+So `Rabbit` now provides access to the static methods of `Object` via `Rabbit`, like this:
 
 ```js run
 class Rabbit extends Object {}
@@ -67,7 +67,7 @@ alert ( Rabbit.getOwnPropertyNames({a: 1, b: 2})); // Error
 
 So `Rabbit` doesn't provide access to static methods of `Object` in that case.
 
-By the way, `Function.prototype` has "generic" function methods, like `call`, `bind` etc. They are ultimately available in both cases, because for the built-in `Object` constructor, `Object.__proto__ === Function.prototype`.
+By the way, `Function.prototype` also has "generic" function methods, like `call`, `bind` etc. They are ultimately available in both cases, because for the built-in `Object` constructor, `Object.__proto__ === Function.prototype`.
 
 Here's the picture:
 
diff --git a/1-js/09-classes/03-static-properties-methods/article.md b/1-js/09-classes/03-static-properties-methods/article.md
index 5a5f27852..bf1f20ccd 100644
--- a/1-js/09-classes/03-static-properties-methods/article.md
+++ b/1-js/09-classes/03-static-properties-methods/article.md
@@ -109,6 +109,17 @@ Static methods are also used in database-related classes to search/save/remove e
 Article.remove({id: 12345});
 ```
 
+````warn header="Static methods aren't available for individual objects"
+Static methods are callable on classes, not on individual objects.
+
+E.g. such code won't work:
+
+```js
+// ...
+article.createTodays(); /// Error: article.createTodays is not a function
+```
+````
+
 ## Static properties
 
 [recent browser=Chrome]
diff --git a/1-js/13-modules/01-modules-intro/article.md b/1-js/13-modules/01-modules-intro/article.md
index fede84069..e9b7272b9 100644
--- a/1-js/13-modules/01-modules-intro/article.md
+++ b/1-js/13-modules/01-modules-intro/article.md
@@ -272,7 +272,7 @@ In other words:
 - module scripts wait until the HTML document is fully ready (even if they are tiny and load faster than HTML), and then run.
 - relative order of scripts is maintained: scripts that go first in the document, execute first.
 
-As a side-effect, module scripts always "see" the fully loaded HTML-page, including HTML elements below them.
+As a side effect, module scripts always "see" the fully loaded HTML-page, including HTML elements below them.
 
 For instance:
 
diff --git a/2-ui/1-document/07-modifying-document/5-why-aaa/task.md b/2-ui/1-document/07-modifying-document/5-why-aaa/task.md
index f87074dba..861f70503 100644
--- a/2-ui/1-document/07-modifying-document/5-why-aaa/task.md
+++ b/2-ui/1-document/07-modifying-document/5-why-aaa/task.md
@@ -22,6 +22,6 @@ Why does that happen?
   alert(table); // the table, as it should be
 
   table.remove();
-  // why there's still aaa in the document?
+  // why there's still "aaa" in the document?
 </script>
 ```
diff --git a/2-ui/3-event-details/1-mouse-events-basics/article.md b/2-ui/3-event-details/1-mouse-events-basics/article.md
index c322126e4..77dda0a91 100644
--- a/2-ui/3-event-details/1-mouse-events-basics/article.md
+++ b/2-ui/3-event-details/1-mouse-events-basics/article.md
@@ -52,7 +52,7 @@ Click-related events always have the `button` property, which allows to get the
 
 We usually don't use it for `click` and `contextmenu` events, because the former happens only on left-click, and the latter -- only on right-click.
 
-From the other hand, `mousedown` and `mouseup` handlers may need `event.button`, because these events trigger on any button, so `button` allows to distinguish between "right-mousedown" and "left-mousedown".
+On the other hand, `mousedown` and `mouseup` handlers may need `event.button`, because these events trigger on any button, so `button` allows to distinguish between "right-mousedown" and "left-mousedown".
 
 The possible values of `event.button` are:
 
@@ -154,7 +154,7 @@ Move the mouse over the input field to see `clientX/clientY` (the example is in
 
 ## Preventing selection on mousedown
 
-Double mouse click has a side-effect that may be disturbing in some interfaces: it selects text.
+Double mouse click has a side effect that may be disturbing in some interfaces: it selects text.
 
 For instance, double-clicking on the text below selects it in addition to our handler:
 
diff --git a/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/solution.view/index.html b/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/solution.view/index.html
index e998165fd..84d52b18c 100644
--- a/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/solution.view/index.html
+++ b/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/solution.view/index.html
@@ -54,7 +54,7 @@
 
     <p>Once upon a time there was a mother pig who had three little pigs.</p>
 
-    <p>The three little pigs grew so big that their mother said to them, "You are too big to live here any longer. You must go and build houses for yourselves. But take care that the wolf does not catch you."
+    <p>The three little pigs grew so big that their mother said to them, "You are too big to live here any longer. You must go and build houses for yourselves. But take care that the wolf does not catch you."</p>
 
     <p>The three little pigs set off. "We will take care that the wolf does not catch us," they said.</p>
 
diff --git a/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/source.view/index.html b/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/source.view/index.html
index 2dc4394e7..774e24a21 100644
--- a/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/source.view/index.html
+++ b/2-ui/3-event-details/3-mousemove-mouseover-mouseout-mouseenter-mouseleave/1-behavior-nested-tooltip/source.view/index.html
@@ -54,7 +54,7 @@
 
     <p>Once upon a time there was a mother pig who had three little pigs.</p>
 
-    <p>The three little pigs grew so big that their mother said to them, "You are too big to live here any longer. You must go and build houses for yourselves. But take care that the wolf does not catch you."
+    <p>The three little pigs grew so big that their mother said to them, "You are too big to live here any longer. You must go and build houses for yourselves. But take care that the wolf does not catch you."</p>
 
     <p>The three little pigs set off. "We will take care that the wolf does not catch us," they said.</p>
 
diff --git a/2-ui/3-event-details/4-mouse-drag-and-drop/article.md b/2-ui/3-event-details/4-mouse-drag-and-drop/article.md
index 9789e1c2d..e9a23ad63 100644
--- a/2-ui/3-event-details/4-mouse-drag-and-drop/article.md
+++ b/2-ui/3-event-details/4-mouse-drag-and-drop/article.md
@@ -100,7 +100,7 @@ ball.style.left = pageX - ball.offsetWidth / 2 + 'px';
 ball.style.top = pageY - ball.offsetHeight / 2 + 'px';
 ```
 
-Not bad, but there's a side-effect. To initiate the drag'n'drop, we can `mousedown` anywhere on the ball. But if "take" it from its edge, then the ball suddenly "jumps" to become centered under the mouse pointer.
+Not bad, but there's a side effect. To initiate the drag'n'drop, we can `mousedown` anywhere on the ball. But if "take" it from its edge, then the ball suddenly "jumps" to become centered under the mouse pointer.
 
 It would be better if we keep the initial shift of the element relative to the pointer.
 
diff --git a/2-ui/3-event-details/7-keyboard-events/article.md b/2-ui/3-event-details/7-keyboard-events/article.md
index 86e9b83fd..12fe63201 100644
--- a/2-ui/3-event-details/7-keyboard-events/article.md
+++ b/2-ui/3-event-details/7-keyboard-events/article.md
@@ -149,7 +149,7 @@ The `onkeydown` handler here uses `checkPhoneKey` to check for the key pressed.
 
 As we know, the `false` value returned from the event handler, assigned using a DOM property or an attribute, such as above, prevents the default action, so nothing appears in the `<input>` for keys that don't pass the test. (The `true` value returned doesn't affect anything, only returning `false` matters)
 
-Please note that special keys, such as `key:Backspace`, `key:Left`, `key:Right`, do not work in the input. That's a side-effect of the strict filter `checkPhoneKey`. These keys make it return `false`.
+Please note that special keys, such as `key:Backspace`, `key:Left`, `key:Right`, do not work in the input. That's a side effect of the strict filter `checkPhoneKey`. These keys make it return `false`.
 
 Let's relax the filter a little bit by allowing arrow keys `key:Left`, `key:Right` and `key:Delete`, `key:Backspace`:
 
diff --git a/3-frames-and-windows/06-clickjacking/article.md b/3-frames-and-windows/06-clickjacking/article.md
index 1daa87dd0..34d0a91ae 100644
--- a/3-frames-and-windows/06-clickjacking/article.md
+++ b/3-frames-and-windows/06-clickjacking/article.md
@@ -154,7 +154,7 @@ Depending on your browser, the `iframe` above is either empty or alerting you th
 
 ## Showing with disabled functionality
 
-The `X-Frame-Options` header has a side-effect. Other sites won't be able to show our page in a frame, even if they have good reasons to do so.
+The `X-Frame-Options` header has a side effect. Other sites won't be able to show our page in a frame, even if they have good reasons to do so.
 
 So there are other solutions... For instance, we can "cover" the page with a `<div>` with styles `height: 100%; width: 100%;`, so that it will intercept all clicks. That `<div>` is to be removed if `window == top` or if we figure out that we don't need the protection.
 
diff --git a/4-binary/03-blob/article.md b/4-binary/03-blob/article.md
index e3bd32b38..41ad4b36e 100644
--- a/4-binary/03-blob/article.md
+++ b/4-binary/03-blob/article.md
@@ -101,7 +101,7 @@ For each URL generated by `URL.createObjectURL` the browser stores a URL -> `Blo
 
 A generated URL (and hence the link with it) is only valid within the current document, while it's open. And it allows to reference the `Blob` in `<img>`, `<a>`, basically any other object that expects a URL.
 
-There's a side-effect though. While there's a mapping for a `Blob`, the `Blob` itself resides in the memory. The browser can't free it.
+There's a side effect though. While there's a mapping for a `Blob`, the `Blob` itself resides in the memory. The browser can't free it.
 
 The mapping is automatically cleared on document unload, so `Blob` objects are freed then. But if an app is long-living, then that doesn't happen soon.
 
diff --git a/6-data-storage/01-cookie/article.md b/6-data-storage/01-cookie/article.md
index 2667b6948..b88849457 100644
--- a/6-data-storage/01-cookie/article.md
+++ b/6-data-storage/01-cookie/article.md
@@ -282,7 +282,6 @@ Here's a small set of functions to work with cookies, more convenient than a man
 
 There exist many cookie libraries for that, so these are for demo purposes. Fully working though.
 
-
 ### getCookie(name)
 
 The shortest way to access a cookie is to use a [regular expression](info:regular-expressions).
diff --git a/6-data-storage/02-localstorage/article.md b/6-data-storage/02-localstorage/article.md
index 412f44c16..e4a4b3558 100644
--- a/6-data-storage/02-localstorage/article.md
+++ b/6-data-storage/02-localstorage/article.md
@@ -6,7 +6,7 @@ What's interesting about them is that the data survives a page refresh (for `ses
 
 We already have cookies. Why additional objects?
 
-- Unlike cookies, web storage objects are not sent to server with each request. Because of that, we can store much more. Most browsers allow at least 2 megabytes of data (or more) and have settings to configure that.
+- Unlike cookies, web storage objects are not sent to server with each request. Because of that, we can store much more. Most modern browsers allow at least 5 megabytes of data (or more) and have settings to configure that.
 - Also unlike cookies, the server can't manipulate storage objects via HTTP headers. Everything's done in JavaScript.
 - The storage is bound to the origin (domain/protocol/port triplet). That is, different protocols or subdomains infer different storage objects, they can't access data from each other.
 
diff --git a/7-animation/2-css-animations/article.md b/7-animation/2-css-animations/article.md
index 8dd64f39a..1b1b0ca0d 100644
--- a/7-animation/2-css-animations/article.md
+++ b/7-animation/2-css-animations/article.md
@@ -210,7 +210,6 @@ Other names are shorthands for the following `cubic-bezier`:
 
 So we could use `ease-out` for our slowing down train:
 
-
 ```css
 .train {
   left: 0;
@@ -226,6 +225,7 @@ But it looks a bit differently.
 The control points on the curve can have any `y` coordinates: even negative or huge ones. Then the Bezier curve would also extend very low or high, making the animation go beyond its normal range.
 
 In the example below the animation code is:
+
 ```css
 .train {
   left: 100px;
diff --git a/8-web-components/5-slots-composition/article.md b/8-web-components/5-slots-composition/article.md
index ada52a06a..871ac711a 100644
--- a/8-web-components/5-slots-composition/article.md
+++ b/8-web-components/5-slots-composition/article.md
@@ -130,6 +130,7 @@ For example, the second `<span>` here is ignored (as it's not a top-level child
 If there are multiple elements in light DOM with the same slot name, they are appended into the slot, one after another.
 
 For example, this:
+
 ```html
 <user-card>
   <span slot="username">John</span>