yGen came about when I realised most of my web pages had multiple repeated elements. E.g. the header, menu bar, sidebar and so on. So, yGen is a combination text editor and compiler, generating finished files (be they html, text, PHP or any extension you like) from template files and includes. Includes can be nested, allowing you to build complex files from duplicated parts - without manually duplicating anything.
yGen is not a wysiwyg web site creation tool. All coding is by hand so knowledge of html syntax is essential. yGen has a few other tools: upload selected or all files to your site (via FTP), automatically add 'title' tags to all links (improves visibility in search engines), direct editing of css and include files, link highlighting, table building Wizard and more.