The species problem (the two questions, do species exist and, if yes, according to what criteria do two individuals belong to the same species) is one of the oldest questions in biology. Darwin's 'Origin of the Species' was - and still is - one of the most comprehensive answers to this problem. However, even Darwin's work cannot satisfactorily explain many of the speciation questions. Over the years, many concurrent taxonomic systems have evolved each of them particularly well suited for the speciation of certain groups of organisms but all of them fail to provide a universal answer to all questions relating to speciation. Do Species Exist? is a readily comprehensible guide for a wide audience of biologists, field taxonomists and philosophers, giving an excellent overview of the species problem without delving into the many feuds between the different schools of taxonomy.