What the meaning of the "!" in < ! DOCTYPE html>?

Question

Because I had to change him for: <DOCTYPE ! html> in the code for the css to stay correct how I wanted.

Answer 1

So... The code was constructed outside the default? Because the default is <! doctype html> isn't ?

Answer 2

thanks!

Answer 3

im not sure what the ! mean but it just a name for it .. ti write comment.