Why keyword letters should be lower case letter

Question

Because while coding using case operator ,I used C👈ase hence I get invalid

Answer 1

Many languages are case sensitive, so if you use SoloLearn as your variable name, for example, then you reference it as "sololearn" later on, you will get an error because the cases are not the same.

Answer 2

Please add the language.

As far as I know, in all languages it makes a big difference whether something is written in small or large letters. If the syntax dictates that a keyword be written in lower case, then you have to lower case.