The term "macro photography" is often used to describe any close-up shot. However, in DSLR photography, it should really only be used to describe a photograph with a 1:1 or higher magnification.
Macro photography is commonly used by still life DSLR photographers to capture small details of objects. You'll also see it used to photograph flowers, insects, and jewelry, among other items.
If you own a DSLR camera, the easiest way to achieve macro shots is to buy a designated macro lens. Typically, macro lenses come in either a 60mm or 100mm focal length. However, they are not cheap, costing anywhere from $500 to several thousand! They will obviously give the best and sharpest results, but there are a few alternatives.
The cheapest way to get macro shots is to buy a close-up filter to screw onto the front of your lens. They are designed to allow closer focus, and they come in various strengths, such as +2 and +4. It's best to use only one at a time, as too many filters can cause the quality of the glass in your lenses to deteriorate. While the quality won't be as good as with a dedicated macro lens, you'll still achieve usable shots.
If you have a little more to spend, you could consider investing in an extension tube. These will increase the focal length of your existing lens, while effectively moving the lens farther away from the camera sensor, allowing for higher magnification. As with filters, it is advisable to only use one extension tube at a time, so as not to cause deterioration in image quality.
Users of compact, point and shoot cameras can also take macro photographs as most of these cameras have a macro mode setting on them. In fact, it can be far easier to achieve a 1:1 magnification with compact cameras, because of their built-in zoom lenses.
When photographing macro subjects, you should always remember to use a tripod or pod beanbag, allowing for a steady camera and sharp images. Photographers should also remember that depth of field will be far more obvious with small objects. A small aperture will be needed to leave the subject in focus, while blurring the background.