The commonly used file system in macOS is the Apple File System (APFS). It was designed specifically for solid-state drives (SSDs) and offers features such as encryption, space efficiency, and the ability to manage large volumes of data seamlessly. APFS also supports cloning of files and directories, allowing for quick duplication without using extra storage. As macOS has evolved, APFS has significantly improved the operating system's performance and user experience, making it a vital component for managing files and applications effectively.