Firefox 2.0x is also known as the "stable" build.
This only gets updated once in a while for
security and stability fixes.
The development builds are also known as trunk.
They are updated every day and where all the new
work goes. Once in a while one of these builds is
chosen to become a new alpha or beta release for
Firefox, but in reality you can see what's
happening every day if you want to. Eventually
(hopefully by November or so) the code going into
these builds will be stabilized and become Firefox 3.
You can use a development build to see what we're
working on, and to help us test.
If you install it, please install in a separate
directory from your normal Firefox!!!! You don't
want to use it for your daily browsing. It's no
fun to crash when you're doing something important.
You can see which one you have by looking at