A wide variety of WYSIWYG ("what you see is what you get") editors are available for use by CMS developers. Some are open source, some are proprietary, and some are a part of a hosted service. We list here only those that are "through-the-web" browser-based editors. Desktop applications like Macromedia Dreamweaver and Contributor will be covered in another section.
Most of the available editor widgets are for HTML editing. Some are XHTML compliant, and some are XML editors.
Some references for cross-browser solutions.