# What is a media type in EPUB?

Source: https://epublab.com/glossary/media-type/ (updated 2026-11-03)

A media type (MIME type) such as application/xhtml+xml, image/jpeg or text/css tells the reading app what each file in an EPUB is. Every manifest item declares one, and it must match the file's real content.

## Why it matters when you convert a PDF to EPUB

A converter that writes a PNG image but declares it as image/jpeg, or labels a chapter text/html instead of application/xhtml+xml, produces an EPUB that validators reject and some readers mishandle. EPUB 3 also lists core media types that need no fallback.