For reaching Osiris where the border blocks Tor.
Some ISPs and some countries block Tor entry. A bridge routes your connection through a relay that is not on the public list of Tor nodes, which hides that you are using Tor.
Use a bridge when Tor Browser cannot connect, connects very slowly, or when the Tor Project site is blocked where you are. If Tor is not blocked, skip it, because a bridge only adds latency.
Open the connection settings, choose to use a bridge, pick the built-in obfs4 option or request one from the Tor Project, and restart. A bridge changes how you reach Tor but nothing about verifying an Osiris node.
