For human beings, hair has always been a sign of vitality and power. Besides communication and adornment, one of its main functions is to protect the organism against environmental influences. This volume gives insight into the molecular and cellular basis of the complex mode of hair formation and degeneration, its growth and protective role. Attention is focussed on the cytoskeleton, the keratinization process, cell-cell adhesion and communication, pigmentation, morphology and histochemistry, all of which are vital for the stability or the cosmetic treatment of human hair. Furthermore, the molecular basis of diseases is described, to assist in treatment and possibly genetic counselling services.