CSS is an acronym for Cascading Style Sheets, a language used as a formatting tool for HTML (HyperText Markup Language) and other markup languages that has been endorsed by the World Wide Web Consortium (W3C). A CSS document serves as a master plan for the styles and layout used on a webpage or website. Site-wide style decisions are iterated once and applied many times, saving work for the site designer and time in rendering the site. A CSS editor is a tool for creating or editing a CSS document, and it can make the workflow better for creating CSS stylesheets.
CSS editors can be fairly bare bones — some developers just use a text-editing program — or include syntax highlighting to help create and check code, a CSS wizard, and validation. Being able to organize sections of code in folders can make maintenance easier, and previews in one or more browsers can assist in achieving a universally workable design. This may or may not be facilitated with a split window that allows viewing of two browsers at once.
On occasion, a lite version can be found as a free download, acting as a demo for a pro version. There are also CSS editors that are better adapted for newcomers and others that are more apt for professionals. Useful templates and/or example stylesheets from W3C can be very helpful. In 2010, CSS was in version 2 and version 3 is being developed, so web designers planning to work in version 3 need to check to make sure that the CSS editor they plan to use supports that version.