Spin Structure of the Nucleons from Hermes

A summary of results from the HERMES experiment is presented. Measurements of inclusive and semi-inclusive asymmetries have provided precise information on the nucleon spin structure functions g₁(x) for the proton, neutron and deuteron and on the polarized parton distributions Δq(x) for each quark flavor. First indications of the size and the sign of the gluon polarization are also reported. Finally, the first measurements of single spin azimuthal asymmetries in semi-inclusive pion production provided new insights into new distribution and fragmentation functions.