Macro photography is simply photographing something small, like an insect.

Almost all manufacturers make Macro lenses. Why they call them Macro is beyond me, since the goal is to photograph small objects. Nikon more accurately calls its close-focusing lenses "Micro" lenses.

Normal lenses can only get within a few feet of a subject.  If you’re trying to photograph an ant, this isn’t nearly close enough.  A good macro lens will project an image on the camera’s sensor that is at least half the size of the object being photographed, a ratio of 1:2.  Most good macro lenses can achieve a ratio of 1:1, and some much higher than this. Beware of lenses that claim that they are "Macro" but only produce a ratio of 1:4 or even worse.

These lenses claim that they are macro because when the image is blown up to normal photo size, the image is larger than the object photographed. BS is what I say.

So how do you get beautiful images of small objects? The best way is to buy a dedicated macro lens, of course. But that's too easy. What if you're on a budget, like the rest of the universe?

Try reversing the lens! You can buy adapters that allow you to mount your lens BACKWARDS on your camera. They screw on to the threads that normally mount filters on the front of your lens. This sounds absolutely crazy at first. But take your lens, detach it from your camera, flip it around, and hold it against the camera body. Now see if you can focus on really close objects. Eureka! The drawbacks are that you will lose metering and autofocus, which is usually fine if you are photographing static objects. But the adapters are dirt cheap, and they add a lot of versatility to the lenses the you already have.

You can also buy an extension tube to place between the camera and the lens. Since this tube is hollow (no glass in it) it is quite cheap. As the lens gets farther from the camera, the closer the focusing distance becomes. A downside is that you lose the ability to focus at infinity. Some extension tubes will preserve quotfocus and metering, so be careful when buying them.

Using a teleconverter can also help you magnify the image. As usual, you will lose two stops of light.

The third, least desirable option is to buy a close-up filter (basically an accessory lens) that acts like a pair of reading glasses for your camera, allowing it to focus on close objects. They come in different powers just like reading glasses (+1, +2, +3, +4 dipoters), and screw on to the front of your lens just like a filter would. These can work fairly well, but they do add another element for the light to travel through and add distortion (worse in the higher powers), so they will come nowhere close to the quality of a true macro lens. And some of the cheaper ones offer rather poor optical quality.

As you increase magnification, depth of field decreases. Just think of a microscope, where a few microns one way or the other makes the difference between in focus and not. So not all of your shot may be in focus. The key is to try to focus on the most important element in your photograh, such as the eyes.