Filter module

When string data is added to a field that supports text formats, the data is saved and preserved as it was originally entered. Enabled filters for a text format will not be applied until the content is viewed. Drupal works in such a way that it saves the original content and only filters on display.

With the Filter module enabled, you gain the ability to specify how text is rendered based on the roles of the user who created the text. It is important to understand the filters applied to a text format that uses a WYSIWYG editor. For example, if you selected the Display any HTML as plain text option, the formatting done by the WYSIWYG editor would be stripped out when viewed.