The Klingon cultural database was a repository of information found aboard Starfleet vessels. It described many aspects of Klingon culture, including rituals and important milestones in the lives of Klingons.
In 2365, Wesley Crusher consulted the database aboard the USS Enterprise-D when looking for information to determine a reason that Worf was in a bad mood. After research, he found that the time was approaching for the tenth anniversary of Worf's Age of Ascension, and because Worf was not among other Klingons, he felt culturally isolated. The information in the database would be used by Wesley to program a holodeck simulation of a celebration of the anniversary, which Worf put himself through. This succeeded in improving his mood. (TNG: "The Icarus Factor")