An initiative that started in 2000 to devise a set of rules for naming groups of organisms based explicitly on their evolutionary (i.e. phylogenetic) relationships, rather than on traditional rank-based codes of nomenclature. Its chief aim is to give each clade of organisms—i.e. an ancestor and all its descendants—a unique and unchanging name that will exist alongside rank-based classifications. Such a system will, it is claimed, avoid the ambiguities and confusion that arise due to continual taxonomic revisions and prevent different groups being given the same name. This will enhance the efficient storage and retrieval of the vast and ever-growing amounts of biological data drawn from across the entire tree of life.