If you are running Drupal 7 and trying to install the CKEditor, you may find an error message.
You may find the message that “CKEditor could not be detected” when you visit the wysiwyg module. Looking throughout the net, I found that lots of people have found this error. It seems it has happen various times that CKEditor updated their code. After trying several “fixes” found on the net, I found each was for different version of CKEditor than I had download. Even the latest suggestion that the error was trivial to fix by adjusting wysiwyg module’s version detection did not solve the problem. Some fixes resulted in white screens and were a pain to recover from. After trying several time consuming fixes (most of the time spent trying to find the fix), I decided to downgrade to a working version of CKEditor.
You may want to try installing the latest version of CKEditor with the latest version of wysiwyg module, the problem could be resolved with any update of wysiwyg module. However, if you find the problem, you may want to simplify your fix by a downgrade to CKEditor 3.6.6.1 (found at the bottom of the linked page). This 3.6.6.1 is available, will load without problems with wysiwyg module as late as 7.x-2.2, and will probably do what you need … provide a wysiwyg editor.
PS … if you are installing, make certain you do not activate the ckeditor module and wysiwyg module. Activating both modules will result in an error.