This is an article about physical control.
The joystick is a physical control that has a stick or handle in the middle that can be tilted in any direction (possibly, with some constraints set). Basically, it is a tool that converts its physical tilt in two values that correspond to two axes that are mutually perpendicular to each other.
Joysticks may have extra controls on them, like buttons, scrolling wheels. The handle can be rotated around its axis. Also, some feedback functions can be added to it, like servos to put the joystick to necessary position according to the state of the system, or vibration motors to give tactile feedback.
Joysticks are produced in multiple sizes, some of them are compact and controlled by fingertip, while others are large and are controlled by full hand.
Joysticks variants are primary means of handling construction machinery, cranes, tugboats, military equipment, and unmanned aircraft. Also, they replace steering wheels in some airplane cockpits.
If the control surface has a joystick, it is not recommended to position extra controls or touch screens right behind it, because it can be hard to reach them, especially if the surface is positioned quite high (or the operator is sitting in front of it).
Also, it is important to test the reliability of joystick if a huge force is applied to it, especially by operator under stress conditions.