It is a social convention1 that local variables be named likeThis.
That is if their name is one word, that word should be in lowercase.
String apple = "Red Delicious";If it is multiple words, the first word should be lowercase and the others should start with a capital letter.
This convention is called camelCase because the capitals looks like the humps on a Camels back.
Just like proper formatting, sticking to this style will increase your chances of someone online being able to help you with your code.