Coding a web site by hand does not require any special tools. If you have a text editor, you’re ready to get started - at least that's the theory. In practice you're likely to find that you are switching from text editor to browser to check previews, moving to a dedicated CSS editor to adjust style sheets and flicking to various other related applications.
Coda is a little different. It has been designed with hand coders in mind. The editor itself feature syntax colouring, line numbering and auto-complete, and you can make use of 'clips' to access frequently used sections of code. There's also an advanced find ad replace tool that makes it easy to make quick changes across an entire site.
Site previewing is built into the program so there's no need to fire up Safari and the integrated CSS editor means that styling your web site can also be achieved from the same program. File management is handled by the sidebar, and FTP, SFTP, FTP+SSL, and WebDAV support means that Coda can be used to create a wide variety of different sites.
A built in terminal makes it possible to run MySQL queries or debug PHP from the same program used to create a site - all of this is wrapped up in an instantly accessible interface. Coda is powerful and usable in its own right, but it can be great extended through the use of plugins.