It's Dreamweaver. Dreamweaver let's you create template pages that you can use to create a site. When you fcrete a template, you define "editable regions". These regions are marked in the code like what you posted above. You can create new pages based on your template, and you're only able to edit the stuff inside the editable regions. The cool part is that if you need to change the template (say, add another link to a sidebar) you open the template, make your changes, andw hen you save it, Dreamweaver automatically updates every file that is based on that template to include the new changes. The editable regions define the content that is unique to each page, and the template defines the content that is the same on every page.