Please guys, what is the function of *comment* in Javascript and html

Question

Javascript

Answer 1

//comments are used to document your code and make it easier for you & other programmers to understand the given program(code) in question.
life is simple with comments, comment your code so people don't have to read your 100's, 1000's(let's not go in million's okay... XD) lines of code without any documentation(comment) good luck understanding the huge program .

Answer 2

Comments are invisible... So I don't still understand its usefulness... Pls explain better