Macro photography begins with a macro lens. Let's say you want to photograph a praying mantis up close -- close enough to capture its insectoid eyes and interesting legs. What would happen if you stuck a camera with a regular zoom or wide-angle lens right up against the praying mantis and tried to snap off a picture? Well, you'd probably scare it off! But even if the mantis stuck around, you wouldn't get a very good picture, because your camera won't be able to focus at extremely close range with one of those lenses. Enter the macro.
The simplest (and least expensive) macro lenses simply screw onto other camera lenses and magnify images, allowing the camera to focus on small subjects from greater distances. These are often called close-up lenses or macro filters. Real macro lenses are different. Instead of screwing onto the end of another lens like a filter, macro lenses attach to a camera in place of a zoom lens or wide-angle lens and specialize in bold close-ups.
A real macro lens for a digital SLR camera can cost hundreds of dollars, but it gives a photographer the ability to take close-up shots in perfect focus. For example, the Canon EF-S 60mm f/2.8 Macro can focus on objects a mere .65 feet (19.8 centimeters) away. The longer EF 100mm f/2.8L Macro has to be a whole foot (30.5 centimeters) away to focus. But that's not necessarily a bad thing, depending on how you want to use the lens. Shooting from further away gives you more working distance, and is better for skittish subjects.