This is a personal, guided tour of biological classification, not a quick-and-dirty manual, nor a comprehensive account of the history of systematic biology. This a reflection on why and how we classify extinct and extant organisms. I wish to explore alternative views of hierarchy, permanence and delineation of categories, and the use of data. I hope to convince you that biological classifications are necessary tools, but also strong ideological statements. The prevailing approach to classification at any time reflects distinct views on nature, how it is organized, and how you use information.