Viral diseases are so common we know them by name: AIDS, influenza, measles, polio, rabies, smallpox, chickenpox, and yellow fever. These are only a few of the diseases that viruses are known to cause, and if we were to estimate the number of people who have died from viral diseases over the past 200 years, it would exceed the mortalities caused by wars and all other diseases combined. And yet, these masters of death and disease have also done some good: they have helped shape our ecosystems and our genomes, they have accelerated the rate at which all organisms have evolved, and they have helped scientists discover the genes that cause cancer. Biotechnology, gene therapy, and some forms of stem cell therapy all depend on viruses, and together those procedures are being used to find cures for cancer, cardiovascular disease, neurological disorders, and many other diseases. Viruses describes the structure, function, and evolution of viruses with an emphasis on their dual role as infectious microorganisms and important members of Earth's biosphere. Coverage includes the origin of viruses, viral structure and behavior, viral taxonomy, and the history of virology. This comprehensive new resource also examines marine virology, the use of viruses in biomedical research, viral diseases, and modern methods for fighting viral infections. Viruses devotes an entire chapter to viral pandemics, a topic that the general public has recently become interested in as health agencies, such as the World Health Organization (WHO), release annual bulletins regarding the threat of possibly deadly viral strains. The final chapter provides background material on cell biology, biotechnology, methods in virology, and other relevant topics.