Taxonomy is the study of the classification of organisms. Taxonomists study the characteristics of organisms in order to classify them into the appropriate taxonomic groups, such as kingdom, phylum, class, etc.
Binomial nomenclature is a system of naming a species using two names, the genus and the species (and sometimes subspecies), which make up the scientific name of a species. Examples include Panthera tigris for the tiger, and Canis lupus for the gray wolf.
Phylogeny, or phylogenetics, is the study of the evolutionary development of organisms and relationships between them. Phylogeny is a useful tool for taxonomists.