Preface; 1. Spin and helicity; 2. The effect of Lorentz and discrete transformations on helicity states, fields and wave-functions; 3. The spin density matrix; 4. Transition amplitudes; 5. The observables of a reaction; 6. The production of polarized hadrons; 7. The production of polarized e±; 8. Analysis of polarized states: polarimetry; 9. Electroweak interactions; 10. Quantum chromodynamics: spin in the world of massless partons; 11. The spin of the nucleon: polarized deep inelastic scattering; 12. Two-spin and parity-violating single spin asymmetries at large scale; 13. One particle inclusive transverse single-spin asymmetries; 14. Elastic scattering at high energies; Appendices.