Epstein-Barr virus (EBV) is a human gamma herpes virus that is best known for being the causative agent of infectious mononucleosis in man. A fascinating feature of this virus is its ability to persist in the host, and it is estimated that more than 95% of adults are carriers of the virus. Importantly, EBV can transform latently infected primary cells from healthy individuals into cancerous ones, thereby causing important human cancers such as B-cell neoplasms (e.g. Burkitt's lymphoma and Post-transplant lymphomas), certain forms of T-cell lymphoma, and some epithelial tumors (e.g. gastric carcinomas). Understanding viral latency, what triggers viral reactivation and the mechanism of transformation of normal host cells into malignant cells are critical for the development of strategies for the prevention and control of this intriguing virus and related cancers. In this book, expert EBV virologists comprehensively review this important subject from a genetic, biochemical, immunological,