What is Wikidata?
Short answer
A free, structured, machine-readable database run by the Wikimedia Foundation; each entry has a Q-number such as Q42.
It stores facts as data rather than prose: founding date, occupation, official website, identifiers on other platforms.
Its inclusion standard is notability of a different kind — an item must be identifiable by a serious, publicly available reference. That is a far lower bar than a Wikipedia article.
Why it matters
It feeds Knowledge Panels and is read directly by assistants and search engines, so it is often the highest-leverage thing a brand can own.