How does drifting actually work?

So, how does drifting actually work? I've seen it in racing videos and it looks absolutely thrilling, but I'm not quite sure how the car is able to slide around corners like that. Is it all about the tires and how they grip the road, or is there more to it than that? I'd love to know the mechanics behind this high-speed driving technique and how drivers are able to pull it off so effortlessly.