Swiftfox is an optimized build of Mozilla Firefox. Swiftfox has builds for both AMD and Intel processors. The 188.8.131.52 release is based on Firefox 184.108.40.206. The trunk is the most cutting edge of all the builds and is where Firefox 3 is being developed. Branch builds are built from a code base that has been tested much more than the trunk and therefore should be considered to be more stable. The 1.8 branch is where Mozilla develops Firefox 2 which will be the next major Firefox release.