Macro photography, also referred to as close-up photography (although technically speaking, you don't necessarily need to be close up to get a macro shot) is one of the most popular types of photography.
Macro photography can encompass many different types of subjects, from small products and plants to insects and beyond. I think the reason why macro photography is so interesting is that it allows you to see the small details of things that you overlook at first glance. Getting closer to the subject makes these details stand out.
To do macro photography, you need to be able to focus close enough to your subject that the image your lens projects on the sensor of your camera is the exact same size as the subject. The relative size of the actual subject to the projected image is defined in terms of a reproduction ratio. So if your image size is the same as the subject size, you have a ratio of 1:1.
Strictly speaking, the true definition of a macro image is one that has a ratio of 1:1 or better. These days, however, the marketing gurus at the camera and lens manufacturing companies have broadened the definition of macro lens to encompass any lens that allows you get a ratio of 1:2, or half ...