Adobe Dreamweaver is one of the top programs for web developers, if not the best. Dreamweaver is a fully capable web editor that has just about every feature one could ask for. Most notably, Dreamweaver offers three different views to edit code: code, split, and design. Code view is basically just a HTML editor. It utilizes the full window to list HTML, PHP, CSS, etc. Design view is a WYSIWYG (what you see is what you get) editor. Instead of listing code, design view lets your preview HTML and other languages directly within dreamweaver. Split view is a combination of code view and design view. The top portion of split view is reserved for code, and the bottom portion is used as WYSIWIG.
Dreamweaver also has several different interfaces to choose from, which are designed to make specific projects easier. Currently, Dreamweaver has app developer, app developer plus, classic, coder, coder plus, designer, designer compact, and dual screen interfaces to choose from. Each interface repositions and hides/shows/ certain toolbars in order to make a job easier.
Although Dreamweaver offers countless other options, the features above are what set it apart from an average HTML editor. If you want to edit web based code, Adobe Dreamweaver will be compatible 90% of the time.