The International System for Human Cytogenomic Nomenclature (ISCN) provides a standard approach to describe any genomic rearrangement identified by techniques ranging from karyotyping to FISH, microarray, genomic mapping, various region-specific assays, and DNA sequencing. ISCN 2024 is an indispensable reference volume for human cytogeneticists, molecular geneticists, clinical geneticists, technicians, and students for the interpretation and communication of human cytogenomic nomenclature.