- A computer
- A web browser
- A plain text editor
- FTP software
You may consider a text editor that highlights code (such as Coda, TextMate, HTMLKit, and so on), but a simple plain text editor is all that's required. You may like to run a local copy of WordPress on your computer, in which case you may need a server such as Apache and MySQL installed (though WAMP and MAMP can take care of all that for you). But even this is not necessary, as you could do the entire thing remotely.