teI

TEI, the Text Encoding Initiative, is a community-driven framework for encoding texts in digital form. The TEI Guidelines define an XML-based vocabulary for representing the structure, features, and bibliographic metadata of literary, historical, and linguistic works. The framework is designed to be flexible and extensible, enabling scholars to encode diverse text types while preserving interoperability and machine readability.

Originating in the 1980s within the digital humanities, TEI brought together libraries, universities, and researchers to establish a common standard. The Guidelines were first published in 1990 and have evolved through several major revisions, notably TEI P5, which emphasizes modularity, XML-compatibility, and broad language support. The TEI Consortium coordinates ongoing development, reference implementations, and community resources, all under an open, collaborative framework.

Core concepts include the TEI header for metadata and a large body of elements for text encoding, including structure, apparatus, form, annotations, and bibliographic references. TEI supports customization via ODD (One Document Does It), enabling users to define tailored tag sets and generate schemas or documentation from a single source. The framework supports manuscripts, editions, linguistic corpora, and digital editions across disciplines.

TEI is widely adopted by libraries, publishers, and research projects. It interoperates with related standards and projects such as EpiDoc for inscriptions and various TEI-based pipelines that transform TEI XML into HTML, PDF, or other outputs. While not a single file format, TEI's open, extensible approach has made it a leading standard for encoding complex textual objects in the humanities.