The Snowspeeder is used on ice planets. These ships are highly armored and highly maneuverable. Sitting in the front seat is the pilot, who flys the ship. Sitting in the rear seat is a gunner who controls the ship's 2 forward laser cannons, and a rear mounted harpoon.
It became extremely useful on the planet Hoth as a scout and as an attack vehicle. The Snowspeeder was one of the only successful defenses against the Empire's dreaded AT-AT's during the Battle of Hoth. One of the Snowspeeder was flown by Luke Skywalker.