Wormhole

A wormhole is a conduit in space that connects two points of space-time together throught subspace. A wormhole has a mouth at each end of the conduit that allows anything can travel through the wormhole. If a large enough, or stable enough wormhole is found then starships can pass through the wormhole and travel a great distance in relatively little time.

No natural stable wormholes have yet been discovered in the Alpha or Beta Quadrants. In 2366, it was believed that the Barzan wormhole discovered near Barzan II was a stable passage between the Alpha and Gamma Quadrants. The Barzans opened up bidding for the wormhole and the Federation and the Ferengi Alliance were the principal bidders. However, tests by the crew of the USS Enterprise-D revealed that while the Alpha "end" was stable, the other end was constantly moving around, which resulted in a Ferengi team being stranded in the Delta Quadrant. (TNG episode: "The Price").

The only known artificalialy stable wormhole, the Bajoran wormhole, was discovered in the Denorios Belt of the Bajor system by Commander Benjamin Sisko in 2369. Sisko discovered that the wormhole had been constructed by the Prophets, and they would allow traffic to pass through the wormhole into the Gamma Quadrant. (DS9 episode: "Emissary").