A datacard containing the Death Star plans
A data disk, also called a datacard or datadisc, was a compact, portable device utilized for data storage. It was common practice to store chain codes on these devices.
During the events of the Battle of Scarif, the Death Star plans that were successfully extracted by Rogue One were transmitted to the Profundity. Subsequently, these plans were transferred onto a datacard. This datacard was then entrusted to Princess Leia Organa, who later intended to deliver the plans to Obi-Wan Kenobi on the planet Tatooine. When her vessel came under fire from the Imperial I-class Star Destroyer known as the Devastator, she opted to conceal the datacard within the memory banks of the astromech droid R2-D2, immediately after recording a message intended for Kenobi.
In the realm of the non-canon video game Star Wars: Galaxy of Heroes, datacards appear as a game element, holding characters and other items. These range in value from bronzium to chromium packs, and even the more valuable aurodium.