The demoscene is an international computer art subculture focused on producing demos: self-contained, sometimes extremely small, computer programs that produce audiovisual presentations. The purpose of a demo is to show off programming, visual art, and musical skills. Demos and other demoscene productions (graphics, music, videos, games) are shared at festivals known as demoparties, voted on by those who attend and released online.
The scene started with the home computer revolution of the early 1980s, and the subsequent advent of software cracking. Crackers altered the code of computer games to remove copy protection, claiming credit by adding introduction screens of their own ("cracktros"). They soon started competing for the best visual presentation of these additions. Through the making of intros and stand-alone demos, a new community eventually evolved, independent of the gaming and software sharing scenes.
Demos are informally classified into several categories, mainly of size-restricted intros. The most typical competition categories for intros are the 64k intro and the 4K intro, where the size of the executable file is restricted to 65536 and 4096 bytes, respectively. In other competitions the choice of platform is restricted; only 8-bit computers like the Atari 800 or Commodore 64, or the 16-bit Amiga or Atari ST. Such restrictions provide a challenge for coders, musicians, and graphics artists, to make a device do more than was intended in its original design.
The earliest computer programs that have some resemblance to demos and demo effects can be found among the so-called display hacks. Display hacks predate the demoscene by several decades, with the earliest examples dating back to the early 1950s.
Demos in the demoscene sense began as software crackers' "signatures", that is, crack screens and crack intros attached to software whose copy protection was removed. The first crack screens appeared on the Apple II in the early 1980s, and they were often nothing but plain text screens crediting the cracker or their group.