Bacta was an organic chemical substance that consisted of gelatinous, translucent red alazhi and kavam bacterial particles that were mixed within a colorless, viscous fluid known as ambori. When a patient was exposed to bacta, the bacterial particles within sought out wounds and promoted rapid tissue regeneration while preventing the emergence of scar tissue. Bacta was often thought of as a «miracle fluid» and seemed to be effective against almost every type of injury and ailment across an incredible cross-section of species throughout the galaxy. It was considered the best medicine available anywhere, replacing the previously used kolto.
Bacta was invented by the Vratix on the planet Thyferra in antiquity, with the galaxy at large learning of its properties around 4100 BBY. The Vratix were willing to share the technology, but the substance could only be made on their homeworld, where the needed resources were abundant. Struggles on Thyferra were often caused by disputes over control of bacta, often between the two main producers of bacta, the Zaltin Corporation and the Xucphra Corporation, or over the bacta the planet produced. Before its obsolescence, kolto was used along with bacta for medical treatments. Bacta later outsold kolto and eventually replaced it altogether. After the reorganization of the Galactic Republic during the Clone Wars, the new Galactic Empire only allowed bacta to be produced on Thyferra, which was then stockpiled on Bespin.
More than six months after the Battle of Yavin, the Empire’s Moff Kohl Seerdon led an attack against Rebel Alliance’s bacta supplies on Thyferra. Rogue Squadron thwarted the attack, and Seerdon was killed.
At some point, Emperor Palpatine had the chemical sequence for bacta stored at his stronghold on Wayland, possibly intending to develop a weapon to neutralize the properties of the compound. However, his scientists never developed a weapon, and the sequence remained stored on Wayland. When the Yuuzhan Vong War gripped the galaxy, the Yuuzhan Vong conquered the planet Wayland where Shapers managed to analyze the bacta formula whereupon they created a virus that targeted the alazhi plant on a genetic level. This was in order to create a bio-weapon designed to kill anyone who was treated by bacta. However, their plans were thwarted by Klin-Fa Gi along with Uldir Lochett as well as his crew.
During the Swarm War, the Killiks staged a coup against the Thyferran government, which cut off the Galactic Alliance’s supply of bacta during the Battle of Tenupe, thus crippling the medical abilities of the Alliance.