What does a pitcher do?

"Baseball isnt easy. Every pitch is a test of wills between a pitcher and a batter, but pitching is more than just trying to throw a ball very hard. ... This book takes readers onto the pitching mound to stare down the plate, choose a pitch, and try to strike a batter out. It also takes readers through the proper way to throw a baseball and execute the defensive strategy pitchers need to field the ball and make outs if a batter makes contact with a pitch"--Amazon.com.