This book is an introduction to the very extensive subject of information security. With an ever increasing requirement for confidentiality it is easy to see why this subject has become one of the most important in recent times. However, information security is not just about keeping information private but also about its integrity and making it available appropriately. In a society that is demanding increased availability of information in any number of areas and using increasingly complex types of technology including mobile phones, laptops, on the move in trains and aircraft, there will always be growing risks to the information and its security. A compromise must be struck between security of information and its availability but this must be done in a realistic and knowledgeable manner if it is to remain effective. This book, and the ISEB's 'Information Security Management Principles' qualification which it supports, provide significant first steps along the path of dealing with information security in a realistic and comprehensive manner.