A crack intro, also known as a cracktro, loader, or just intro, is a small introduction sequence added to cracked software, designed to inform the user of which "cracking crew" or individual cracker was responsible for removing the software's copy prevention and distributing the crack.
These first appeared on Apple II and later Commodore 64 games that were distributed around the world via Bulletin Board Systems (BBSes) and floppy disk copying. Initially the intros consisted of simple messages, but they grew progressively more complex as they became a medium to demonstrate the purported superiority of a cracking group.
As a result, crack intros began to feature big colourful effects, music, and scrollers. Cracking groups would use the intros not just to gain credit for cracking, but to advertise their BBSes, greet friends, and to give themselves recognition. Messages were frequently of a vulgar nature, and on some occasions made threats of violence against software companies or the members of some rival crack group. Occasionally intros also told players to support the designers of high quality games by buying also a legal copy of software in question. Often trainers appeared with intros. A trainer is a cracker's addition to a game program, which allows the player to make the game easier for example by selecting unlimited lives or unlimited time.
Crack intro music (when present) usually falls into the chiptune genre. In the early days advanced sound chips were unavailable and high quality instrument samples could not be efficiently stored or used. Today chiptune music is used in homage to the original intros. Occasionally, the color palette used in modern intros will also reflect the old video hardware limitations.
Crack intro programming eventually became an art form in its own right, and people started coding intros without attaching them to a crack just to show off how well they could program. This evolved into the demoscene. The separation of demoscene from The Scene is reflected by the fact that many people dealing with software piracy no longer tolerate intros in the releases.
Crack intros that use chiptunes live on today in the form of background music for small programs intended to remove the software protection on commercial and shareware software that has limited or dumbed-down capabilities. Sometimes this is simply in the form of a program that generates a software package's serial number, usually referred to as a keygen.