Too is frequently confused with to and two.

"Too" means also or more.

Correct usage
He would like to go too.
That is too much sugar.
The two children are too near to the fire.
Incorrect usage
The too children are to near too the fire.

"Two" is a number. (It comes after one and before three.) It's also written as "2".

"To" is a preposition indicating something is going or getting nearer to something else.