The Text Encoding Initiative (TEI) is a format in XML designed to help textual scholars encode features of texts. The standard is developed and maintained by a consortium whose chief deliverable is a set of Guidelines which specify encoding methods for machine-readable texts, chiefly in the humanities, social sciences and linguistics. Since 1994, the TEI Guidelines have been widely used by libraries, museums, publishers, and individual scholars to present texts for online research, teaching, and preservation. In addition to the Guidelines themselves, the Consortium provides a variety of resources and training events for learning TEI, information on projects using the TEI, a bibliography of TEI-related publications, and software developed for or adapted to the TEI.
TEI is widely used in digital classicist projects, either in one of its default forms or in a customisation (e.g., EpiDoc).
The community of TEI users uses the TEI-L mailing list as a key communication channel.