  SCUBA-2 is an innovative 10000 pixel bolometer camera operating at
submillimetre wavelengths on the James Clerk Maxwell Telescope (JCMT). The
camera has the capability to carry out wide-field surveys to unprecedented
depths, addressing key questions relating to the origins of galaxies, stars and
planets. With two imaging arrays working simultaneously in the atmospheric
windows at 450 and 850 microns, the vast increase in pixel count means that
SCUBA-2 maps the sky 100-150 times faster than the previous SCUBA instrument.
In this paper we present an overview of the instrument, discuss the physical
characteristics of the superconducting detector arrays, outline the observing
modes and data acquisition, and present the early performance figures on the
telescope. We also showcase the capabilities of the instrument via some early
examples of the science SCUBA-2 has already undertaken. In February 2012,
SCUBA-2 began a series of unique legacy surveys for the JCMT community. These
surveys will take 2.5 years and the results are already providing complementary
data to the shorter wavelength, shallower, larger-area surveys from Herschel.
The SCUBA-2 surveys will also provide a wealth of information for further study
with new facilities such as ALMA, and future telescopes such as CCAT and SPICA.
