Chemical Markup Language (CML) is an XML-based file format specifically designed for representing chemical information, including molecules, reactions, spectra, and computational chemistry results. Developed as an application of Extensible Markup Language, CML provides a standardized, machine-readable way to store and share complex chemical data across different software applications and platforms. It bridges the gap between human-readable chemical structures and computational processing, allowing researchers to embed precise atomic coordinates, bond types, and thermodynamic properties directly into web pages and databases. CML plays a crucial role in modern cheminformatics, bioinformatics, and digital publishing, ensuring that chemical data remains accessible, searchable, and interoperable without relying on proprietary file formats.