Dreamweaver is the market leading professional Web design and development tool. It can be bought as a standalone product, or as part of Macromedia's Studio suite, along with Flash Professional, Fireworks, Contribute and FlashPaper.
Now in version 8, Dreamweaver enables you to work graphically, constructing a site by dragging and dropping objects, or to hard code in HTML, complete with Cascading Style Sheets (CSS). Most developers will do the bulk of the work with the page editor and then tidy it up and add the clever bits by tweaking the code. The program is ideally suited to this approach, as you can have page and code windows open at the same time and can now collapse sections of code, to move quickly about the structure of your site.