The Crystallography Open Database (COD) is an open-access database that collects crystal structures of inorganic, metal-organic, and small organic molecules. It contains approximately 80,000 entries in CIF format, with nearly full coverage of IUCr publications. The COD was established in 2003 in response to a letter by Michael Berndt, aiming to unify previously fragmented databases. It has grown significantly, reaching over 80,000 entries by 2008, with the Predicted Crystallography Open Database (PCOD) containing over 100,000 predicted structures. The COD includes data from the American Mineralogist Crystal Structure Database (AMCSD) and has a volunteer-driven model for data collection and maintenance. The database uses an SQL database and CIF files, with data validated and corrected using tools like CIF2COD. The COD also offers a web-based search interface, mirror sites, and the ability to download data in various formats. The COD and PCOD are open-access, with mirrors available globally. Future developments include automation of data submission, improved search capabilities, and integration of tools for substructure searches. The COD also provides persistent URLs for each structure and allows for the release of atomic coordinates after publication or a one-year delay. The database is supported by the IUCr and various institutions, with ongoing efforts to enhance its functionality and accessibility.The Crystallography Open Database (COD) is an open-access database that collects crystal structures of inorganic, metal-organic, and small organic molecules. It contains approximately 80,000 entries in CIF format, with nearly full coverage of IUCr publications. The COD was established in 2003 in response to a letter by Michael Berndt, aiming to unify previously fragmented databases. It has grown significantly, reaching over 80,000 entries by 2008, with the Predicted Crystallography Open Database (PCOD) containing over 100,000 predicted structures. The COD includes data from the American Mineralogist Crystal Structure Database (AMCSD) and has a volunteer-driven model for data collection and maintenance. The database uses an SQL database and CIF files, with data validated and corrected using tools like CIF2COD. The COD also offers a web-based search interface, mirror sites, and the ability to download data in various formats. The COD and PCOD are open-access, with mirrors available globally. Future developments include automation of data submission, improved search capabilities, and integration of tools for substructure searches. The COD also provides persistent URLs for each structure and allows for the release of atomic coordinates after publication or a one-year delay. The database is supported by the IUCr and various institutions, with ongoing efforts to enhance its functionality and accessibility.