Over time humans have invented tools to help with manual work such as the hammer, wheelbarrow, and the printing press.
Computers are machines that were invented to help with the "thinking work". Instead of moving and manipulating physical things like dirt or stone, computers are designed to manipulate information.
The pioneers of computer-science discovered that to design a "thinking machine" the machine would need to perform four different tasks.
Take in information, store information, process the information and output the results.
From the first wooden computers to modern cell phones today, these four things are common to all computers.
That is what makes a computer a computer.
Input is what the world does or what you do that tells the computer to do stuff.
You can tell a computer what to do with any of these:
All these different inputs give the computer information which is then stored in storage or memory for processing.
When a computer receives input the computer will store that input as data in memory.
After a computer has processed information the processor will send processed information to be store in memory.
A computer's processor takes information from storage/memory manipulates it or changes it using an algorithm. (An algorithm is just a series of commands)
The processed information is then sent back to be stored in storage/memory again.
This continues until the process information is ready to be output.
A computer's output is determined by what the computer is designed to do.
A computer may output to a display with text, photos, videos, games, or even signals to control robots.
When computers connect over the internet. The output from one computer becomes the input to another computer and vise versa.
No matter what a computer looks like or how it acts, the computer is always doing the same four things: