Virus Warning! Any computer user has encountered this message, at least once in his life. Virmakers with the persistence of maniacs produce more and more new varieties of viruses. There is an opinion that it is possible to get rid of them only with the help of complex and expensive latest antivirus programs. This is not entirely true - knowledge of the principles of action and methods of introducing viruses will help to detect and localize them in time, even if there is no suitable antiviral "vaccine" at hand. In this book you will find extensive material on the problem of information protection, considered on both sides of the barricades (both on behalf of the virmaker and the creator of antiviruses).