# libtag {#sec:libtag}

The "libtag" library contains functionality for tagging entries.

The following functionality for entries is provided:

* Adding a tag to an entry
* Removing a tag from an entry
* Fetching the list of tags from an entry
* Checking whether a tag is set in an entry

The following additional functionality is provided:

* Fetching all entries which contain a tag
* Fetching all entries which contain a list of tags
* Fetching all entries which fulfill a set of tag-requirements (either
  present, or not present, chained by logical operators)