Explain dynamic ad insertion (#224)

_i18n/en.yml

@@ -133,7 +133,7 @@ documentation:
     general:
       title: "General"
       intro: "Below, you can find more details about the AntennaPod project."
-      ads: "About ads in AntennaPod"
+      ads: "About advertisements in AntennaPod"
       backup: "Backing up your episodes"
       beta: "Beta testing"
       central-distributed: "Central and distributed podcast apps"

_i18n/en/documentation/general/ads.md

@@ -1,4 +1,19 @@
-The official versions of AntennaPod are completely ad-free and open source! If you are seeing ads, this can have two reasons:
+The official versions of AntennaPod do not insert any ads. The app is developed by volunteers without commercial interest and the project relies on donations to cover costs. As AntennaPod's [source code](https://github.com/AntennaPod/AntennaPod) and [income and expenses](https://opencollective.com/antennapod#category-BUDGET) are public everyone is free to verify this.
 
-- **The podcast publishers added the ads to their shownotes or audio file.** AntennaPod plays podcasts just like they were published by the creators. If they include ads, AntennaPod plays them. We have nothing to do with those ads, so the revenue fully goes to the publishers of your podcast.
-- **You downloaded an unofficial version of AntennaPod.** AntennaPod is open-source. This means that anyone can download the source code. Unfortunately, some developers take AntennaPod, insert ads and then publish it as a new app. You can get the official AntennaPod app on [Google Play](https://play.google.com/store/apps/details?id=de.danoeh.antennapod) or [F-Droid](https://f-droid.org/packages/de.danoeh.antennapod/). You can even get the latest release on [GitHub](https://github.com/AntennaPod/AntennaPod/) and build AntennaPod yourself!
+If you are seeing ads, this can have two reasons:
+
+### 1. You downloaded an unofficial version of AntennaPod
+
+AntennaPod is open-source. This means that anyone can download the source code. Unfortunately, some developers take AntennaPod, insert ads and then publish it as a new app. You can get the official AntennaPod app on [Google Play](https://play.google.com/store/apps/details?id=de.danoeh.antennapod) and [F-Droid](https://f-droid.org/packages/de.danoeh.antennapod/). You can even get the latest release from [GitHub](https://github.com/AntennaPod/AntennaPod/) and build AntennaPod yourself!
+
+### 2. The podcast publishers added the ads to their shownotes or audio file
+
+AntennaPod plays podcasts just like they were published by the creators. If they include ads, AntennaPod plays them. We have nothing to do with those ads, so the revenue fully goes to the publishers of your podcast.
+
+Now, you might ask something like "But then why is the podcast in English and the ad in German?" or "But why is the podcast episode from 2008 but still promotes a product released in 2023?". The reason is a technique called _dynamic ad insertion_. Podcast publishers can instruct the hosting company to insert those ads. Then, while downloading or streaming the episode with AntennaPod, the media file delivered to AntennaPod gets cut on-the-fly to include the ads. The ads are recent (while the episode might not be) and can be targeted based on the IP address from which you request the media file (e.g. a company in your country). Depending on how smart the hosting company does this, the ads might get inserted right in the middle of a sentence. Some of the hosting companies also mess up the chapter marks while inserting the ads (so the chapters are off by the duration of the ad).
+
+You can always use the fast forward button in AntennaPod to skip the ads. If you are streaming an episode instead of downloading, the hosting company has an idea of how far you are in the podcast. It might be possible that the company detects the fact that you skipped the ad and insert a new one. If you instead download the episode, they cannot do that and you can skip the ads more reliably. (Downloading is also better for your privacy because then the hosting company does not know when you listen to which section of the episode. AntennaPod can be configured to automatically download and later delete episodes, so you don't have to do that manually.)
+
+Additionally, many podcast hosts provide an ad-free feed that you can buy. Usually, you then either get a secret podcast feed URL, or alternatively username and password that you can enter in AntennaPod.
+
+If you find these ads annoying, consider talking to the podcast publishers about this.