INTRODUCTIONIMGT standardized keywords have been defined for the identification of immunoglobulins (IG) and T cell receptors (TR) and conventional genes. These keywords are based on the concepts of identification, generated from the IDENTIFICATION axiom of the Formal IMGT-ONTOLOGY or IMGT-Kaleidoscope that postulates that any molecule, cell, tissue, organ, organism, or population, any process and any relation, has to be identified. Most of the IMGT standardized keywords used for the identification of sequences and structures are names of IMGT-ONTOLOGY leafconcepts (a leafconcept is a concept that corresponds to the finest level of granularity). IMGT standardized keywords have been essential for the data entries into the IMGT databases and tools, and particularly into IMGT/LIGM-DB, the first and the largest IMGT database that contains IG and TR nucleotide sequences and the translation of annotated sequences. IMGT standardized keywords for IG, TR, and conventional genes are defined in the context of the IMGT-ONTOLOGY concepts of identification.