The 27 Types of Spin
How many basic types of spin are there when someone serves to you? The simple answer is that, in theory, there are 27. In practice, there are 25. (Before we go farther, here's my article "Everything You Ever Wanted to Know About Spin But Were Afraid to Ask." If you are new to the idea of spin, or don't really know what corkscrewspin is - also known as deviation spin - you might want to read it.) In reality, of course, there are an infinite number of spins, but they can generally be categorized as these 27. In fact, you can narrow this down to three main types of spin - topspin/backspin, sidespin left or right, and corkscrewspin left or right. All spins just varying amounts of these three main types.
You don't really need to worry about identifying these 27 or 25 spins when receiving. When I list 27 different spins, these are only of theoretical and intellectual interest. When reading spin, you don't have to identify which combos of these spins it is. You simply have to read the direction the ball is spinning and how fast it is spinning, and then react to it. That's it.