Virology covers all aspects of the virus from evolution, structure, life cycle and function to the diseases that they are responsible for and the host defenses against them. Viruses are infectious particles that are loaded with genetic material ( DNA or RNA) that insert themselves into host cells, splice themselves into the host genome and get themselves replicated. The various structures and all of the places of the life cycle of the viruses is important in virology both for classification and for inventing ways to destroy the virus or limit its damaging effects.

Classification, which is a major part of virology, can be done in several ways. One way is in terms of the host organisms that the virus infects, such as animals, plants, fungi and bacteria. Each of these different types of cell is different so each presents a different challenge to the virus in its efforts to get replicated. Viruses can also be classified in terms of the genetic material present. They may have, for example, a single or double strand of RNA or DNA. Besides host organism and the type of genetic material the shape of the virus is also used in classification.

The key job in virology is to go beyond classification and to use all the knowledge of the virus and its activities and effects to discover ways to destroy it, prevent transmission of it, or at the very least to prevent its detrimental effects.