Book excerpt: This publication extends the now classic system of human cytogenetic nomenclature prepared by an expert committee and published in collaboration with Cytogenetic and Genome Research' since 1963. Revised and finalized by the ISCN Committee and its advisors at a meeting in Seattle, Wash., in April 2012, the ISCN 2013 updates, revises and incorporates all previous human cytogenetic nomenclature recommendations into one systematically organized publication that supersedes all previous ISCN recommendations. There are several new features in ISCN 2013: an update of the microarray nomenclature, many more illustrative examples of uses of nomenclature in all sections some definitions including chromothripsis and duplication a new chapter for nomenclature that can be used for any region-specific assay. The ISCN 2013 is an indispensable reference volume for human cytogeneticists, technicians and students for the interpretation and communication of human cytogenetic nomenclature.