The International ImMunoGeneTics Information System (IMGT) is a high-quality integrated knowledge resource specializing in immunoglobulins (IGs), T cell receptors (TRs), major histocompatibility complex (MHC), and related proteins of the immune system. IMGT includes several sequence databases, a genome database, a 3D structure database, and web resources. It provides expertly annotated data according to the IMGT Scientific chart and IMGT-ONTOLOGY concepts. IMGT is widely used in medical research, veterinary research, biotechnology, diagnostics, and therapeutic approaches. It is freely available at http://imgt.cines.fr. IMGT is developed based on three main biological approaches: genomics, genetics, and structural analysis. The genomics approach focuses on gene-centered studies, the genetics approach on gene sequence polymorphisms and mutations, and the structural approach on 2D and 3D structures of IG, TR, MHC, and RPI. IMGT-Choreography, based on the Web service architecture paradigm, enables dynamic procedure calls between databases and tools. IMGT includes databases such as IMGT/LIGM-DB, IMGT/GENE-DB, IMGT/MHC-DB, IMGT/PRIMER-DB, and IMGT/PROTEIN-DB. It also provides tools for sequence analysis, genome analysis, and 3D structure analysis. Web resources include the IMGT Marie-Paule page, which contains 8000 HTML pages of synthesis, knowledge, and external links. IMGT is used in various domains, including fundamental research, medical research, veterinary research, genome diversity studies, structural evolution of proteins, biotechnology, diagnostics, and therapeutic approaches. IMGT is an important resource in immunogenetics and immunoinformatics, providing standardized data on nucleotide and protein sequences, oligonucleotide primers, gene maps, genetic polymorphisms, specificities, 2D and 3D structures. It is supported by the Centre National de la Recherche Scientifique (CNRS) and other funding bodies. IMGT is cited in scientific literature and is an essential tool for researchers in the field.The International ImMunoGeneTics Information System (IMGT) is a high-quality integrated knowledge resource specializing in immunoglobulins (IGs), T cell receptors (TRs), major histocompatibility complex (MHC), and related proteins of the immune system. IMGT includes several sequence databases, a genome database, a 3D structure database, and web resources. It provides expertly annotated data according to the IMGT Scientific chart and IMGT-ONTOLOGY concepts. IMGT is widely used in medical research, veterinary research, biotechnology, diagnostics, and therapeutic approaches. It is freely available at http://imgt.cines.fr. IMGT is developed based on three main biological approaches: genomics, genetics, and structural analysis. The genomics approach focuses on gene-centered studies, the genetics approach on gene sequence polymorphisms and mutations, and the structural approach on 2D and 3D structures of IG, TR, MHC, and RPI. IMGT-Choreography, based on the Web service architecture paradigm, enables dynamic procedure calls between databases and tools. IMGT includes databases such as IMGT/LIGM-DB, IMGT/GENE-DB, IMGT/MHC-DB, IMGT/PRIMER-DB, and IMGT/PROTEIN-DB. It also provides tools for sequence analysis, genome analysis, and 3D structure analysis. Web resources include the IMGT Marie-Paule page, which contains 8000 HTML pages of synthesis, knowledge, and external links. IMGT is used in various domains, including fundamental research, medical research, veterinary research, genome diversity studies, structural evolution of proteins, biotechnology, diagnostics, and therapeutic approaches. IMGT is an important resource in immunogenetics and immunoinformatics, providing standardized data on nucleotide and protein sequences, oligonucleotide primers, gene maps, genetic polymorphisms, specificities, 2D and 3D structures. It is supported by the Centre National de la Recherche Scientifique (CNRS) and other funding bodies. IMGT is cited in scientific literature and is an essential tool for researchers in the field.