  The GlueX experiment at Jefferson Lab has been designed to study
photoproduction reactions with a 9-GeV linearly polarized photon beam. The
energy and arrival time of beam photons are tagged using a scintillator
hodoscope and a scintillating fiber array. The photon flux is determined using
a pair spectrometer, while the linear polarization of the photon beam is
determined using a polarimeter based on triplet photoproduction.
Charged-particle tracks from interactions in the central target are analyzed in
a solenoidal field using a central straw-tube drift chamber and six packages of
planar chambers with cathode strips and drift wires. Electromagnetic showers
are reconstructed in a cylindrical scintillating fiber calorimeter inside the
magnet and a lead-glass array downstream. Charged particle identification is
achieved by measuring energy loss in the wire chambers and using the flight
time of particles between the target and detectors outside the magnet. The
signals from all detectors are recorded with flash ADCs and/or pipeline TDCs
into memories allowing trigger decisions with a latency of 3.3 $\mu$s. The
detector operates routinely at trigger rates of 40 kHz and data rates of 600
megabytes per second. We describe the photon beam, the GlueX detector
components, electronics, data-acquisition and monitoring systems, and the
performance of the experiment during the first three years of operation.
