Polarised structure functions

This talk discusses the current understanding in some aspects of polarised lepton-nucleon deep inelastic scattering. The first section focuses on the non-singlet part of available spin dependent structure function data. The results, though consistent with theoretical predictions in this sector, are extremely sensitive to extrapolation of the data to thex→1 region and seem to indicate that the quarksdo carry a very small fraction of the nucleon spin. We then review the formalism of DIS processes with emphasis on the gluon sector.