CKEditor module: CKEditor is the successor to FCKeditor and has its own CKEditor module. The FCKeditor module will not receive any new features, nor will it be updated for Drupal 7. Upgrading to CKEditor is recommended for all users of FCKeditor.
WYSIWYG editor
This module allows Drupal to replace textarea fields with the FCKeditor - a visual HTML editor, sometimes called WYSIWYG editor. This HTML text editor brings many of the powerful WYSIWYG editing functions of known desktop editors like Word to the web. It's relatively lightweight and doesn't require any kind of installation on the client computer.
Note: This module is not affiliated with the WYSIWYG module. WYSIWYG offers in principle the same: an FCKeditor (or other editors) instead of normal textareas. The approach of WYSIWYG is slightly different, and users unsatisfied with the FCKeditor module are encouraged to try out the WYSIWYG module (and vice versa).
Demo site
Please visit the demo site to see a sample installation of Drupal with FCKeditor enabled.