  The Qweak experiment at Jefferson Laboratory measures the parity violating
asymmetry of polarized electrons scattering from a proton target at very low
momentum transfer. In the Standard Model, this asymmetry reveals the proton's
coupling to the neutral vector current, the weak charge. This value, measured
directly for the first time, will provide a precision test of the Standard
Model and will constrain the possibility of relevant physics beyond the
Standard Model. The planned precision will probe certain classes of new physics
at the ~2 TeV scale. In order to challenge the precise predictions, the
asymmetry will be measured with a 2.5 percent accuracy. To achieve such a
precision, great care has to be taken on many aspects of the experiment. The
very low momentum transfer reduces the hadronic effects to the asymmetry and
must be determined to half of a percent accuracy. Beam stability is controlled
and monitored constantly and background events are carefully studied.
