  In this paper we describe the system design and capabilities of the
Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the
conclusion of its construction project and commencement of science operations.
ASKAP is one of the first radio telescopes to deploy phased array feed (PAF)
technology on a large scale, giving it an instantaneous field of view that
covers 31 square degrees at 800 MHz. As a two-dimensional array of 36x12m
antennas, with baselines ranging from 22m to 6km, ASKAP also has excellent
snapshot imaging capability and 10 arcsecond resolution. This, combined with
288 MHz of instantaneous bandwidth and a unique third axis of rotation on each
antenna, gives ASKAP the capability to create high dynamic range images of
large sky areas very quickly. It is an excellent telescope for surveys between
700 MHz and 1800 MHz and is expected to facilitate great advances in our
understanding of galaxy formation, cosmology and radio transients while opening
new parameter space for discovery of the unknown.
