Authority control systems assign a unique identifier to each topic, to allow precise identification of topics, and enable more accurate searches. The entries typically correspond to people, book titles, and similar well-defined entities.

The{{Authority control}} template links Wikipedia articles to the corresponding entries inlibrary catalogs ofnational libraries and otherauthority files all over the world. This is why you may see several code numbers listed. As an example, the Wikipedia authority control information for theAlexander Graham Bell article looks like this:

To add this auto-updating template to your user page, use{{totd b}}