Transporter is primary Starfleets way for quickly transporting equipment and personell from and to starships. There are 2 types - personell and cargo transporters.
Transporter is able to transport matter from one place to another, and can even transport energy/particle beam of hand phaser, as seen in TNG episode "Datalore".
There are many things that can prevent successful transport, like shields (unless shield frequency is known). However, in "Dark frontier" Voyager apparently succeded in bypassing Borg shields and transporting photon torpedo onboard. Subsequent explosion destroyed vessel due to torpedo being near power matrix - original plan was only to disable it and salvage whatever equipment they were able to find. (unfinished)
Personnell transporter
(unfinished)
Cargo transporter
(unfinished)
