Highlights from the COMPASS Experiment

An update is given of the ongoing experimental investigation of the spin structure of the nucleon carried on by the COMPASS Collaboration at CERN. Both longitudinal and transverse spin phenomena are covered. In the first case, the hot topic is the direct measurement of the gluon polarisation. Evidence is presented for $\Delta G/G$ being small around $x_{g}\simeq$ 0.1, and its first moment should not be larger than 0.2–0.3 in absolute value. About transverse spin effects, evidence is given for new phenomena, associated with transverse momentum dependent distribution and fragmentation functions.