Why use the ! operator thing when I could just flip the statement it's referencing?

Question

For example,

If (!(age > 18))

Why wouldn't I just put (age < 18)

Answer 1

Then it wouldn't be included, right? So, then
If (!(age > 18))
Is the same as
If (age is =< 18)
Right?

Answer 2

You're absolutely right, I mean <=. Still quite new to this, my apologies!