What does pairs and ipairs do?

Hi. I’m kind of new to the lua language. I’m starting to understand classes and I’m wondering what ipairs and pairs are and how to use them. I’m guessing they’re types of loops but i may be wrong.

https://coolcodea.wordpress.com/2013/04/07/26-tables/

And a more technical explanation

http://www.lua.org/pil/7.3.html

Thanks! I’ll look at these right now.