A robot may include a feedback-driven connection between sense and action, not under direct human control, although it may have a human override function. The action may take the form of electro-magnetic motors or actuators (also called effectors) that move an arm, open and close grips, or propel the robot. The control and feedback system is provided by a computer program run on either an external or embedded computer or a microcontroller. By this definition, a robot may include nearly all automated devices.

Two basic ways of using effectors are to move the robot around (locomotion) or to move other objects around (manipulation). This distinction divides robots into two mostly separate categories: mobile robots (moving) and manipulator robots (grabbing). The most notable exception to this rule is the self-reconfigurable robot which potentially is able to use its effectors in three basic ways: locomotion, manipulation and self-reconfiguration, where the robot changes its own shape and/or function to better solve the task at hand.

Alternately, robot has been used as the general term for a mechanical man, or an automaton resembling an animal, either real or imaginary. It has come to be applied to many machines which directly replace a human or animal in work or play. In this way, a robot can be seen as a form of biomimicry. Lack of anthropomorphism is perhaps what makes us reluctant to refer to the highly complex modern washer-dryer as a robot. However, in modern understanding, the term implies a degree of autonomy that would exclude many automatic machine tools from being called robots. It is the search for ever more highly autonomous robots or cognitive robots which is the major focus of robotics research and which drives much work in artificial intelligence.

The term robot is also often used to refer to sophisticated mechanical devices that are remotely controlled by human beings, such as waldoes and ROVs, even though these devices are not autonomous.