The ContentHandler facility provides a way to represent the content of a wiki page, and the various ways in which that content can be interpreted, or transformed. For example, in which format to store it in a database, and how to render the content as HTML.
This includes the Content and ContentHandler interfaces, and those implementations that are part of MediaWiki core.
For how content objects are stored and their association with pages and edits, see MediaWiki-Core-Revision-backend.
See also:
Parent project: MediaWiki-General