While saving a text in notepad, what does encoding mean and how do you know which one to choose

Question

Html

Answer 1

Encoding means that you are going to convert something into a code.
And what do you mean what to choose?

Answer 2

Utf-8 is a character encoding in Html5 that is capable of encoding unicodes
the previous HtMl does not require utf-8

Answer 3

Since you mentioned Notepad, I'm assuming you were referring to text/character encoding, wiki has a good intro about it:
https://en.m.wikipedia.org/wiki/Character_encoding

Answer 4

For example UTF - 8
What does it mean