Artificial limbs are a type of prosthesis and are classified by the type of amputation they would replace, for example

• Transtibial: Below the knee
• Transfemoral: Above the knee
• Transradial: below the elbow
• Transhumeral: above the elbow

For congenital (from birth) defects the terms are used to refer to the body part that would be amputated. For example if one of the limbs is very short and the foot is at the level of the 'normal' shin then the prosthesis would be described as a transtibial prosthesis even though the Tibia is fully intact.

Any artificial limb is attached to a persons body, to replace a missing part of the body. They used to be made from wood and certain types of metal, but have now been replaced with more lightweight material such as fibreglass.

Artificial limbs in the past had no mobility. Then they were replaced with models that had joints and so could be bent (if unnaturally and not automatically) and fixed in different positions for different types of activities (for example, sitting and walking). These, in turn, were replaced with robotic models capable of moving by themselves when controlled by an internal computer or directly by the user. In the past they could be controlled either by other muscles (for example, on the back), but today direct neural control is preferable.

How artificial limbs are operated by direct neural control: Limbs and appendanges are moved by muscles, which are stimulated by very small amounts of electricity (microvolts) from the nervous system. Even if the limb or appendage is absent, the nerves and impulses controlling the missing limb are (usually) still there, and the brain can send microvolts of electricity to guide a "phantom" limb. If these currents are amplified and sent to a motor in the artificial limb, that limb can be moved via the same method used to control natural limbs. The current challenge for medical science is to perfect the system, as refining the technology is an ongoing process.

In most instances, modern artificial limbs can restore full functionality. For example, American pilot Andrew Lourake returned to his job as a jet pilot after he was fitted with C-Leg robotic leg.

Many people in developing countries, particularly victims of landmines, can't afford even the most basic artificial limbs.

In 2004 a dolphin in the Okinawa Churaumi Aquarium, who lost most of its fin because of necrosis, got an artificial fin that allows it to swim as fast as a healthy dolphin can and jump from the water.