Briefly, a monopod is like a walking cane for a camera. It is a fast and easy way to balance a heavy camera without setting up a regular tripod. They are probably best suited for those large heavy telephoto/zoom lenses that usually have a screw mount right on the lens barrel. Most photographers when using them, keep them attached to the camera, ready to shoot. Then they just plant, aim and shoot. They also are good in cramped areas where the spread legs of a tripod won't fit.