I don't really ever remember learning this word in English class growing up as a native speaker in the US.  

It's just a common word that we have and use a lot!

"Got" is a word that we use all the time!  It is a really "popular" word to use in non-formal speech, not just using it formally.

For example, "I got it"  (means I understand!) / "gotcha!"

To need something ...  "I just gotta have this!" (I just got to have this / I just need to have this)

I've got to get going now ... ;)

/Nadine