This~ It's a program for graphic design that allows you to create artwork out of vectors. This means that instead of making lines with pixels like you would in photoshop, the program converts the lines you draw into math equations that can be scaled up and down infinitely. It's really nice for posters and stuff like that because you can blow something up really big and it'll still be super crisp. It's kind of not as intuitive as traditional art programs but I'm a huge fan. Especially for design/typography it's a must-have tool IMO. It's pretty expensive, especially if you're only just getting started with vectors, but I'm sure there's a freeware version of it out there somewhere.
tl;dr - it's a computer program for graphic design, gives you very crisp images, kinda not as intuitive as others.