The grappler was a piece of technology used on starships to move objects. The grappler consisted of a shaft with claws on one and a launcher.
In 2151, the Enterprise used the grappler on various occasions. These occasions included snagging a Suliban ship, attempting to recover Shuttlepod 1 from a comet, and again to recover a shuttlepod from a Klingon hijacker. (ENT episodes: "Broken Bow", "Breaking the Ice", "Sleeping Dogs")
In 2159, Starfleet had developed tractor beam technology, rendering the grapplers obsolete. The Enterprise was refitted and her grapplers were replaced by tractor beams. Shortly after the Enterprise left spacedock, the tractor beam was used to pull the USS Coto out of a protostellar nebula. (ST video game: Legacy)