Implants are things that you put in your body to change it. Some are permanent whereas others last only for a short period. They are relatively hard to get and occasionally illegal, but a smart person with open eyes can usually figure out where to get them.
All implants fall into one of three categories: Cybernetics, Bioenhancements, and Nanotechnology. Cybernetic Implants are robotic things, used when steel and algorithms work better than your natural body. Bioenhancements, on the other hand, instead of replacing organic materials, work with them to maximize their natural abilities. Nanotechnology is sort of a mix between the two. It uses nanobots, which are robots, but it uses them mainly to heal or maximize your body, instead of replacing it.
Cybernetics are usually in the form of robotic versions of body parts. Their effects are usually permanent. Bioenhancements are usually in the form of chemicals you consume or inject. Their effects are usually short-lasting but powerful and offensive. Nanotechnology is usually healing or restorative related and last until their benefits are depleted.