This story shows how several different types of clamps are used in assembling built-ins.
Clamping is as important to sound joinery as machining and gluing. Glue alone will hold two pieces of wood together, but a good bond requires pressure to force the glue into the wood's fibers. Clamping also holds a project's parts in proper position until the glue dries and anchors them.
Walk the tool aisle in a home center and you'll find dozens of clamp types and sizes. You won't need them all, but you should have the essentials shown here.
For large projects such as bookcases and cabinets, use bar clamps or pipe clamps. A band clamp is versatile; it can even bind cylinders. Spring clamps are always useful for holding small assemblies together.
You can find many more types of specialty clamps. As with all tools beyond the basics, buy clamps only as you need them.