If you've got a houseful of doors to outfit with hinges, a router and a hinge template are what you need to get the job done quickly. But these tools are expensive, and they require setup time. If you're installing only one or two doors, you can mortise the hinges just as fast using a sharp chisel.
Unlike most cutting tools, a wood chisel is not fully sharpened at the factory. For fine carpentry work, the back of the chisel must be perfectly flat, and the beveled side must be razor sharp. Plenty of jigs are available to ease the sharpening process, or you can send your chisels to a local sharpening service.
Becoming proficient with a chisel is useful for more than just hinges. Among other things, the mortising and carving techniques shown here can be used to install strike plates.