Define actuators with the help of an example. What do you understand by revolute and prismatic joint?

Actuators are components of a robot that help it move and perform actions by converting electrical signals into mechanical motion. For example, motors are actuators that help a robot move its wheels or arms.

A revolute joint is a joint that allows rotational movement between two links, similar to the movement of a door hinge. A prismatic joint is a joint that allows linear (sliding) movement between two links, similar to the movement of a piston.