Creeper was the first

computer worm A computer worm is a standalone malware computer program that replicates itself in order to spread to other computers. It often uses a computer network to spread itself, relying on security failures on the target computer to access it. It wi ...

, while Reaper was the first

antivirus Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware. Antivirus software was originally developed to detect and remove computer viruses, hence the name. ...

software, designed to eliminate Creeper.

Creeper

Creeper was an experimental computer program written by Bob Thomas at BBN in 1971. Its original iteration was designed to move between DEC

PDP-10 Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, especi ...

mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterpris ...

s running the TENEX operating system using the

ARPANET The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first networks to implement the TCP/IP protocol suite. Both technologies became the technical foun ...

, with a later version by

Ray Tomlinson Raymond Samuel Tomlinson (April 23, 1941 – March 5, 2016) was an American computer programmer who implemented the first email program on the ARPANET system, the precursor to the Internet, in 1971; It was the first system able to send mail be ...

designed to copy itself between computers rather than simply move. This self-replicating version of Creeper is generally accepted to be the first

. Creeper was a test