RTML is a language for describing web sites. Like HyperTalk, it is designed to be easy for users with no programming experience. It is, however, quite a powerful language. In Viaweb, every object (e.g. an item or section) has an RTML template that describes what its Web page should look like. An RTML template yields ordinary HTML as its output, but with RTML you can describe complex pages that would be impossibly burdensome to express directly in HTML, either by hand or with a WYSIWYG authoring tool. RTML is a real programming language, not just a page description language (though it can be used simply as a page description language). As well as tags, it has variables, conditionals, iteration, subroutines, math operators, and so on. RTML makes it possible to define the structure of a whole site, not just the contents of individual pages. RTML can generate images, as well as tex...