Base Content Types

There are five base content types: Web Page, Image, File, XML Document, and Post. A website administrator can customize the fields and still retain its status as a base type.

Base Type	Assigned to:
Web Page	Basic Web page, with title, description, file name, and body.
Image	Basic image file with title and description. Used for content that can be uploaded as a file of base type Image and that can be used in Web pages. The file type must be GIF, JPEG or PNG. (Any other types of images must be uploaded as base type File.)
File	Basic binary file with title and description. Used for content that can be uploaded as a file and does not fall into the Image or Web page base types. The types of files you can upload include PDF, CSS, JS, PPT, SWF, audio files, and others.
XML Document	A skeleton file used to publish non-XML site content as XML (an "XML feed"), by means of a list of non-XML content items that references an XML-specific display template. Items of the XML Document type are edited in source mode only, and render as XML without requiring display templates or wrappers.
Comment	A unique content item that is assigned to comments that site visitors contribute. Unlike the other content types, a Comment cannot be edited once it is submitted. It also cannot be used to create an extended content type.