Contents :
1. Pre-history
2. Transversity versus helicity
3. The massless limit. "Cardan" and "see-saw" transformations
4. Transversity distribution delta q(x). The diquark spectator model
5. Soffer inequality
6. Tensor charge sum rule
7. t-channel analysis
8. Selection rules for delta q(x) measurements
9. Evolution with Q squared
10. Quark polarimetry. The sheared-jet (Collins) effect
11. Single-spin asymmetries in inclusive experiments
12. Quark distribution dependent on both spin and transverse momentum
13. First evidence of quark transversityComment: 20 pages, 7 figures. Lecture given at Xeme Seminaire Rhodanien de
Physique "Le Spin en Physique", 3-8 March, Torino, Italy. To appear in the
proceeding
