inode number

An inode number is a unique identifier assigned to each file or directory on a Unix-like operating system. Think of it as a label or address that points to the specific data about the file—such as its size, permissions, owner, and location on the disk—without containing the file’s name. The filename is stored separately in directory listings, which link the name to the inode. This system allows the OS to efficiently organize, access, and manage files, even if filenames change, by relying on these unique inode numbers as stable references within the file system.