What is a Computer?
It is not so simple a question. Is your cell phone a computer? How about your car? Your watch? Your train pass? Are you a computer? What defines a computer, and where do we draw the line between a "computer" and "electronic parts"?
One definition of "computer" has to do with the functions it performs. A computer should have input (the ability to accept information from the outside), output (the ability to deliver data to a user); it must be able to process (change) data; and it must be able to store and retrieve data. If a device is missing one of these functions, it is not fully a computer.
Another key definition of a computer is that it must be programmable. It must be able not only to run a program (a set of instructions), it must be able to run any program. This makes the computer flexible, able to carry out any number of different tasks.