“Virology is progressing under the comfortable simplifications or reductionism and the disturbing recognition of complexity. Viruses are ubiquitous and diverse, and individual viral populations are exceedingly complex and dynamic, both genetically and phenotypically. As intracellular infection events are scrutinized at the single cell level of analysis, we are learning that virus-cell-organism interactions are multifaceted and intricate. Bioinformatics emerges to rescue virology amid a turmoil of new information in need of order. This book, edited by Manja Marz and Dimitrij Frishman, with outstanding contributing authors, will play the role of a lighthouse in a stormy ocean, to guide virologists on possible paths to follow.” -- Esteban Domingo, Professor of Research at the Spanish National Research Council (CSIC), Madrid, Winter 2021