ISO/IEC 9899 is the international standard for the programming language C. It defines the syntax, semantics, and library functions of C, ensuring consistency and portability across different platforms and compilers. The standard is maintained by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). The standard has undergone several revisions since its initial release in 1989, with updates to improve language features and address modern programming needs. Each version, such as C99 and C11, introduces enhancements while maintaining backward compatibility, making it easier for developers to write efficient and reliable code.