# Content Types

The General > Content Types preference page allows you to edit content types, their associated file names and character sets as well as associate arbitrary file names or file extensions with content types. A content type acts as a description of a certain class of files (for instance, XML files). Eclipse uses this description in various scenarios such as editor look up and file comparing.

To access the Content Types preference page select Window > Preferences > General > Content Types. Here is what the Content Types preference page looks like:

By selecting a content type in the topmost tree you can alter the file names and extensions that are associated with it. Note: Certain items will be marked as "locked". An item is locked if it is one of the associations provided by the plug-in that declares the content type. In other words, only user-contributed associations may be removed.

Adding an association is as simple as clicking Add.... A dialog will be shown prompting you to enter the file name or extension.

In addition to adding and removing file names or extensions, you may also set the default encoding for a given content type. To do this, simply enter the encoding name in the provided field and click Update.