There are several types of hand saws, but you won't need them all; the thing you need to know about is their teeth -- specifically, the number of teeth per inch (tpi). A saw's tpi will tell you what material it can cut, how well it will cut it, and how smooth the edge will be. Saws with finer teeth leave a cleaner cut. For example, a rip saw's teeth will aggressively cut through wood but will leave a rough edge, whereas the teeth of a crosscut saw, designed for general use, are finer than those of the rip saw and leave a smoother edge.
Looking for a versatile hand saw for cutting through materials other than wood? Reach for a hacksaw, which can cut through materials such as PVC and even metals including copper or cast-iron piping. Hacksaws also offer replaceable saw blades (important when you're cutting through materials that dull them), and interchangeable blades (important if you want blades of different sizes).