What is input or input device?

INPUT : 

Whatever goes into the computer. Input can take a variety of forms, from commands you enter from the keyboard to data from another computer or device. A device that feeds data into a computer, such as a keyboard or mouse, is called an input devices.

INPUT DEVICES : 

Any machine that feeds data into a computer. For example, a keyboard is an input device, whereas a display monitor is an output devices. Input devices other than the keyboard are sometimes called alternate input devices. mice, trackballs, and light pens are all alternate input devices.

Example of input devices :