A wormhole is a conduit that exists outside normal spacetime and connects two distant points together. The conduit is shorter than the distance between the two points allowing for rapid transit between the two points.
By the 2420s, a new type of transporter technology had been developed, called the subspace-aperture transporter. The technology harnessed wormholes for transporting personnel and, presumably, cargo. (Star Trek: Phoenix: "Cloak and Dagger")