A <em>content entity</em> (or more commonly, <em>entity</em>) is an item of content data, which can consist of text, HTML markup, images, attached files, and other data. Content entities are grouped into <em>entity types</em>, which have different purposes and are displayed in very different ways on the site. Most entity types are also divided into <em>entity sub-types</em>, which are divisions within an entity type to allow for smaller variations in how the entities are used and displayed. For example, the <em>Content item</em> entity type that stores page-level content is divided into <em>content type</em> sub-types; the <em>Custom block</em> entity type has <em>custom block types</em>; but the <em>User</em> entity type (for user profile information) does not have sub-types.