What exactly is Mitosis and Meiosis for Biology?

Today was the first day on learning cell reproduction and I learned about Mitosis and Meiosis. However, I get some of the stuff about it but I don't quite get the whole mitosis and meiosis stuff. What exactly are both of them and I'd love to know information about them like how they work together, and etc. It wasn't like I didn't pay attention, in fact, I did and I don't mean to brag but I have the highest grade in the cl so ya...I do pay attention a lot. Anyways, please do not give me answers like wikipedia where the words are way too fancy and hard. I want some straight, given and easy to understand explanations. Thank You.