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What Is a Computer?
A computer takes in data, processes it, stores it and gives out information — the input–process–output model.
A Simple Definition
The key words are input, process, output and storage. Every computer does these four jobs — a laptop, a phone, a bank's cash machine, and even the small computer inside a washing machine.
A computer does nothing on its own. It follows a program: a list of instructions written by a person. The computer is very fast and never gets bored, but it cannot think for itself. It does exactly what the program says — even when the program is wrong.
The Input–Process–Output Model
The input–process–output model
| Input, process, output in everyday machines | |||
|---|---|---|---|
Data and Information
A computer turns data into information. Processing can mean sorting, adding up, comparing, searching or formatting. The average of 35, 42, 38 and 40 is 38.75. Add a label and a unit, and the data becomes information that someone can act on.
Hardware and Software
Software comes in two main kinds:
- System software runs the computer itself. The operating system (Windows, Linux, macOS, Android) is the most important example. Utility programs such as antivirus and backup tools are system software too.
- Application software helps a person do a task: writing a letter (Word), managing accounts (a spreadsheet), editing photos (Photoshop), browsing the web.
Hardware without software is a box that does nothing. Software without hardware has nowhere to run. A computer system needs both — and a user to give it a purpose.
Practice
Choose all that apply.
More lessons in Introduction to Computer Systems · Next: Basic Computer Architecture · Previous: Introduction