Binary - the native language of every respectable computer nerd.
For starters, binary is a number sytem where instead of counting from 0 to 9, you count from 0 to 1. When you reach ten normally, you put two of the numbers next to each other (1 and then 0) and get 10. In binary, when you reach 2, you put them together and get 10 (2).
Well, anyways, in our decimal system every place is ten times the one before it (10, 100, 1000). In binary, it's two times the one before it (10 = 2, 100 = 4, 1000 = 8). In a computer, a low voltage means 0 and a high voltage means 1. You would be suprised how many ways you can use these two numbers, and how much you can do with them if you try. I could explain how all the data is stored, but that itself is probably a huge essay that I am not willing to write.
So if you really want to learn go read a book or ask you local comp sci major or something. (Chances are if your reading this you are a comp sci major). But binary is the greatest thing since sliced bread, if you ask me. I am trying to learn to speak it fluently (using ASCII of course). I think you should do the same.