The ragtime progression (E7-A7-D7-G7) often appears in the bridge of jazz standards (). The III7-VI7-II7-V7 (or V7/V/V/V - V7/V/V - V7/V - V7) circle progression leads back to C major (I) but is itself indefinite in key.
A bridge in popular music is a form of musical notes contrasting with one another.
A bridge in J.S. Bach's Fugue in G major BWV 860, mm. 17-19.