A robot can be defined as a programmable, self-controlled device consisting of electronic, electrical, or mechanical units. More generally, it is a machine that functions in place of a living agent. Robots are especially desirable for certain work functions because, unlike humans, they never get tired; they can endure physical conditions that are uncomfortable or even dangerous; they can operate in airless conditions; they do not get bored by repetition; and they cannot be distracted from the task at hand.

The concept of robots is a very old one yet the actual word robot was invented in the 20th century from the Czechoslovakian word robota or robotnik meaning slave, servant, or forced labor. Robots don't have to look or act like humans but they do need to be flexible so they can perform different tasks.

Early industrial robots handled radioactive material in atomic labs and were called master/slave manipulators. They were connected together with mechanical linkages and steel cables. Remote arm manipulators can now be moved by push buttons, switches or joysticks.

Current robots have advanced sensory systems that process information and appear to function as if they have brains. Their "brain" is actually a form of computerized artificial intelligence (AI). AI allows a robot to perceive conditions and decide upon a course of action based on those conditions.

A robot can include any of the following components:

• effectors - "arms", "legs", "hands", "feet"
• sensors - parts that act like senses and can detect objects or things like heat and light and convert the object information into symbols that computers understand
• computer - the brain that contains instructions called algorithms to control the robot
• equipment - this includes tools and mechanical fixtures

Characteristics that make robots different from regular machinery are that robots usually function by themselves, are sensitive to their environment, adapt to variations in the environment or to errors in prior performance, are task oriented and often have the ability to try different methods to accomplish a task.

Common industrial robots are generally heavy rigid devices limited to manufacturing. They operate in precisely structured environments and perform single highly repetitive tasks under preprogrammed control. There were an estimated 720,000 industrial robots in 1998.

Teleoperated robots are used in semi-structured environments such as undersea and nuclear facilities. They perform non-repetitive tasks and have limited real-time control.

Robots are especially valuable to space exploration. Not only can they travel to environments too hostile or too distant for human explorers, but they can also enhance the work schedule of a manned space mission. Space telerobots perform non-repetitive tasks in semi- to unstructured environments. There is often a variable time delay for instructions between the operator and the robot. These robots need to be dexterous, lightweight and have flexible manipulators. They are usually deployed in hostile environments with excessive heat, radiation, a vacuum and variable lighting. These robots must be able to recover from unplanned events including system faults and errors.