Taxonomy and Systematics

Two closely related terms are central to the science of classification, and though they are sometimes used loosely as synonyms, they describe distinct — if overlapping — activities.

Taxonomy is the branch of biology concerned specifically with the characterisation, identification, classification and naming of organisms. It is the practical, descriptive discipline: given an unfamiliar organism, taxonomy provides the methods to determine what it is, decide which existing group it belongs to (or whether it represents something new to science), and assign it a valid scientific name following internationally agreed rules. The word itself comes from the Greek "taxis" (arrangement) and "nomos" (law/method) — literally, the method of arrangement.

Systematics is the broader field concerned with the diversity of organisms and the evolutionary relationships among them. Where taxonomy asks "what is this organism, and what should we call it?", systematics asks the deeper question "how did this organism come to be the way it is, and how is it related to other organisms?" — it draws on comparative anatomy, embryology, physiology, biochemistry, behaviour, and, increasingly, DNA and molecular sequence data to reconstruct the evolutionary history (phylogeny) connecting different groups of organisms. …