A CAB (Cabinet) file is an archive file format used in Microsoft Windows. It is a single file that can contain multiple compressed files, often used for software installation, system files, and device drivers. CAB files support various compression algorithms, including LZX, MSZIP, and Quantum. They are designed to efficiently package and distribute software components, reducing file sizes and simplifying the installation process. CAB files can also contain digital certificates to verify the authenticity and integrity of the contents. The format is often used by Windows Update, device driver installers, and other system-level utilities. While primarily associated with Windows, tools exist to extract CAB files on other operating systems. The internal structure of a CAB file includes a header, file entries, and data blocks, allowing for efficient extraction of individual files without decompressing the entire archive. The format is designed for reliability and is often used for critical system components.