  The T2K experiment is a long-baseline neutrino oscillation experiment. Its
main goal is to measure the last unknown lepton sector mixing angle
{\theta}_{13} by observing {\nu}_e appearance in a {\nu}_{\mu} beam. It also
aims to make a precision measurement of the known oscillation parameters,
{\Delta}m^{2}_{23} and sin^{2} 2{\theta}_{23}, via {\nu}_{\mu} disappearance
studies. Other goals of the experiment include various neutrino cross section
measurements and sterile neutrino searches. The experiment uses an intense
proton beam generated by the J-PARC accelerator in Tokai, Japan, and is
composed of a neutrino beamline, a near detector complex (ND280), and a far
detector (Super-Kamiokande) located 295 km away from J-PARC. This paper
provides a comprehensive review of the instrumentation aspect of the T2K
experiment and a summary of the vital information for each subsystem.
