This document presents the International Chronostratigraphic Chart published by the International Commission on Stratigraphy. It lists geological eras, periods, epochs, and ages from the present back to the Hadean eon, along with their numerical ages in millions of years. Key points include: - The chart is divided into eons, eras, systems/periods, series/epochs, and stages/ages. - Numerical ages are provided for boundaries throughout the Phanerozoic back to the Proterozoic, with less precise ages for the Precambrian. - Unit boundaries are defined by Global Boundary Stratotype Sections and Points (GSSPs) ratified by the International Commission