- To is a preposition with several meanings, including “toward” and “until.”
- Too is an adverb that can mean “excessively” or “also.”
- Just to be clear: two is pronounced the same as to and too, but it can’t be used instead of either of them because it’s a number.
In the hierarchy of things that drive grammar sticklers mad, to and too are near the top. It’s very common to see them confused, abused, and misused, and not just in YouTube comments or on Reddit.