obfs2 and obfs3 are different versions of the obfsproxy protocol, which is used to make Tor circuits look like another type of connection. You can get the different ones with these links: Regular bridges: https://bridges.torproject.org obfs2 bridges:   https://bridges.torproject.org/?transport=obfs2 obfs3 bridges:   https://bridges.torproject.org/?transport=obfs3 For regular bridges, you copy the ip:port. For obfs2 and obfs3, you also have to copy that word. So for an obfs2 bridge, you'll get this:   bridge obfs2 12.34.56.78:443 You copy and enter into Vidalia "obfs2 12.34.56.78:443". Note: you need a special obfsproxy browser bundle to use obfsproxy bridges on Windows, OS X and non-Tails Linux. Tail 0.18 supports obfs2 and obfs3 out of the box.