Why using marks in coding

Question

https://sololearn.com/compiler-playground/Wm5Jp94QX1qr/?ref=app

Answer 1

Marks?

Answer 2

I think you mean "Comment" not marks. Comment will not render by computer, it's just give explanation to humans (another programmer maybe)

Comment in html <!-- comment here -->
Comment in css /* comment here */
Comment in js goes after // comment here