Epstein-Barr virus (EBV) is a fascinating microorganism, as a 'double-facetted” viral agent. After primary infection, it can persist throughout a person’s lifetime in a latent form, from which it can reactivate following specific stimuli (i.e., immunodepression). Unlike other herpesviruses, EBV reactivates a countless number of times with such a high replication rate that it is unable to be controlled by conventional anti-herpesvirus drugs. Moreover, for various reasons, no vaccine is currently available in the market. This book presents a comprehensive overview of EBV, including information on its potential for oncogenic activity, its various isolates, and possible vaccine candidates.