The International Commission on Stratigraphy (ICS) has developed the International Chronostratigraphic Chart, which provides a global standard for chronostratigraphic units (Systems, Series, and Stages) to define the geological time scale. The chart is essential for expressing geological knowledge and linking regional-scale divisions. It is updated regularly and available on the ICS website (www.stratigraphy.org). The chart includes calibrated numerical ages for unit boundaries, allowing for high-resolution correlation of stratigraphic successions. The chart is used by geologists, students, and the public to understand the Earth's history. The ICS also uses GSSPs (Global Boundary Stratotype Sections and Points) to define boundaries, which are recognized as international geostandards. The chart is designed to visually represent the irregularity of Phanerozoic geological time and the stratigraphic successions that define the units. The chart is updated annually, with version numbers indicating the date of the update. The 2013 version includes new GSSPs and revised numerical ages for several boundaries. The chart is available in multiple languages and can be used for educational and professional purposes. The ICS also provides alternative chart designs for textbook authors and conference use. The chart is protected by copyright and requires authorization for reproduction. The ICS works with various subcommissions to evaluate and approve GSSPs, ensuring that the chronostratigraphic units are precisely defined and globally standardized. The chart is a key tool for international geological communication and is continually refined as new data and techniques become available.The International Commission on Stratigraphy (ICS) has developed the International Chronostratigraphic Chart, which provides a global standard for chronostratigraphic units (Systems, Series, and Stages) to define the geological time scale. The chart is essential for expressing geological knowledge and linking regional-scale divisions. It is updated regularly and available on the ICS website (www.stratigraphy.org). The chart includes calibrated numerical ages for unit boundaries, allowing for high-resolution correlation of stratigraphic successions. The chart is used by geologists, students, and the public to understand the Earth's history. The ICS also uses GSSPs (Global Boundary Stratotype Sections and Points) to define boundaries, which are recognized as international geostandards. The chart is designed to visually represent the irregularity of Phanerozoic geological time and the stratigraphic successions that define the units. The chart is updated annually, with version numbers indicating the date of the update. The 2013 version includes new GSSPs and revised numerical ages for several boundaries. The chart is available in multiple languages and can be used for educational and professional purposes. The ICS also provides alternative chart designs for textbook authors and conference use. The chart is protected by copyright and requires authorization for reproduction. The ICS works with various subcommissions to evaluate and approve GSSPs, ensuring that the chronostratigraphic units are precisely defined and globally standardized. The chart is a key tool for international geological communication and is continually refined as new data and techniques become available.