Crown & bridge is a popular name for a fixed replacement for a missing tooth/teeth structure.
A Crown is usually recommended for grossly damaged teeth due to decay/trauma. It can restore the tooth to a normal function and improve its aesthetics.
Bridge is a fixed replacement for missing teeth. In this procedure, to cover a gap, either side of a tooth is crowned & missing teeth can be attached to it with special connectors.
Depending on the situation there are various different methods to accomplish bridging.