Spin Physics

We review the current situation in polarized scattering experiments. We describe the theoretical interpretation of inclusive deep inelastic processes, the current experimental situation and perturbative analyses which extract structure functions and parton distribution functions. We also discuss various issues such as positivity constraints, small x and the possibility of polarized colliding beam experiments at HERA, semi-inclusive processes, the separation of flavors and the measurement of the gluon polarization, and the possibility of using polarisation experiments to put constraints on new physics.