Computer program

A computer program is a list of instructions that tell a computer what to do. Everything a computer does is done by the instructions of a program. The first computers were made with only one built-in program, but today's computers have memory, which can be used to store many different programs. John von Neumann, a mathematician born in Hungary, came up with this idea in the late 1940s. 

Some common examples of computer programs include:
 Web browsers, like Mozilla Firefox or Chrome
 Word processors, like Microsoft Word or Google Docs
 Video games
 Operating systems, like Microsoft Windows or iOS

A computer program is usually stored as a file on the computer's hard drive. The file contains a list of instructions. When the user runs the program, the computer reads the file does what the instructions tell it to do. These instructions can be very simple, like "add these numbers together" or "save these letters". A computer program is written by a programmer, who combines many of these simple instructions to do complicated things, like talking to the computer's screen and telling it to show a video.

The main part of the computer, the processor, is built to understand instructions written in machine code, meaning very long patterns of ones and zeroes. This is hard for humans to understand, so computer programmers write in a programming language, such as BASIC, C, or Java. Once the program is written, the programmer uses a compiler to turn it into machine code so the computer can read it.

There are also bad programs, called malware, written by people who want to do bad things to a computer. Some are spyware, trying to steal information from the computer. Some try to damage the data stored on the hard drive. Some others send users to web sites that offer to sell them things. Some are computer viruses or ransomware.

 Related pages 
 Computer Science
 Software
 Operating system
 Programming language
 Utility software

 Other websites 
 Computer program Citizendium