A Holocron is an artifact from the Star Wars universe.

A Holocron is a crystal lattice (often in cube form) in which Jedi of old could insert phenomenal quantities of data. The technology to make them is, in the era of the Rebellion, nearly lost. But surviving holocrons contain information of Jedi techniques, blueprints of ancient ships and histories of the universe. They are very valuable. Usually, only Force-attuned users can access a holocron. There exist Sith holocrons which are often in pyramidal form.

In the real world, there is also a continuity/canon database maintained by Lucas Licensing called the Holocron.