  The UKIDSS Galactic Plane Survey (GPS) is one of the five near infrared
Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using
the Wide Field Camera on the United Kingdom Infrared Telescope. It is surveying
1868 sq.deg. of the northern and equatorial Galactic plane at Galactic
latitudes -5<b<5 in the J, H and K filters and a ~200 sq.deg. area of the
Taurus-Auriga-Perseus molecular cloud complex in these three filters and the
2.12 um (1-0) H_2 filter. It will provide data on ~2 billion sources. Here we
describe the properties of the dataset and provide a user's guide for its
exploitation. We also present brief Demonstration Science results from DR2 and
from the Science Verification programme. These results illustrate how GPS data
will frequently be combined with data taken in other wavebands to produce
scientific results. The Demonstration Science includes studies of: (i) the star
formation region G28.983-0.603, cross matching with Spitzer-GLIMPSE data to
identify YSOs; (ii) the M17 nebula; (iii) H_2 emission in the rho Ophiuchi dark
cloud; (iv) X-ray sources in the Galactic Centre; (v) external galaxies in the
Zone of Avoidance; (vi) IPHAS-GPS optical-infrared spectrophotometric typing.
(abridged).
