Rich-text editing, with a RTE, in Drupal (6.x branch) can be achieved through specific integration modules (TinyMCE, FCKEditor, WYMeditor, etc.). The RTE choice depends a lot on the habits of users and developers, but all the modules allowing this integration are using the same methods to integrate in the content management system (replacement of the text areas in the content editing forms) and thus a lot of code is repeated among these different modules. This is why the Wysiwyg API module has been created. It offers a way more generic approach of RTE integration and even allows multiple editors to be used simultaneously with a per input format profile management.