R2-D2 is an
Astromech droid. Its
purpose is to provide
hyperspace navigation for
starfighters, and to do light
repairs. Most Astromech droids have a designation that start with R2 (sometimes just R). Nonetheless, saying "Artoo" undeniably indicates this particular droid.
R2-D2's original
owner appears to be the
Naboo government. By the time of
A New Hope, he and
C-3P0 are owned by
Captain Antilles, are then stolen by
Jawas, and finally come to serve
Luke Skywalker.
Artoo makes excellent use of his
complink abilities throughout each
movie, using it to connect to all manners of
computer systems and gain valuable
information. The first such incident (by movie release) is when he plugs into the
Death Star computers to determine how to disable the
tractor beam that is holding the
Millennium Falcon trapped.
The droid also sports a
bevy of useful
tools, including a
claw and a
welder.