Tor bridges are unlisted entrance relays for networks that block the public Tor relays. Tor Browser can request one itself. The Tor Project also hands them out at bridges.torproject.org after a captcha. obfs4 and Snowflake are transports: they make the first hop look less like a plain Tor connection. That raises the cost of blocking. It does not mean a censor with time and a national firewall will fail.
Bridges get discovered and then blocked. When one stops connecting, ask for another and keep a spare. A bridge is only the entrance. It does not add a stronger anonymity promise than Tor Browser already makes, and a bridge you found on a random blog is somebody else’s computer.
Use one when Tor will not connect. Skip the collection hobby on a network where Tor already works.
