ABSTRACT
Viruses have been found in almost all the major groups of prokaryotic and eukaryotic organisms. The number of distinct viruses that have been described cannot be ascertained with any precision, but the total must be several thousand. There are over 2000 descriptions of viruses infecting bacteria alone. Man has an innate desire to classify and name all of the natural objects which he studies, and viruses are no exception. However, there are many different possible ways of classifying and naming biological objects, and judgments must be made that do not have a strictly scientific basis. Thus there is ample room for differences of opinion, emotional attachment to a particular point of view, and unwillingness to compromise. For these reasons the development of viral taxonomy has been marked by some stormy interludes. In this introductory chapter the development of viral taxonomy over the past half century or so will be outlined and the state the subject had reached at the end of the Fifth International Congress for Virology in Strasbourg, 1981, will be summarized.
