The inode is a data structure in a Unix-style file system that describes a filesystem object such as a file or a directory. Each inode stores the attributes and disk block location(s) of the object's data Filesystem object attributes may include metadata (times of last change, access, modification), as well as owner and permission data.
A file system relies on data structures about the files, beside the file content. The former are called metadata—data that describe data. Each file is associated with an inode, which is identified by an integer number, often referred to as an i-number or inode number.
Inodes store information about files and directories (folders), such as file ownership, access mode (read, write, execute permissions), and file type. On many types of file system implementations, the maximum number of inodes is fixed at file system creation, limiting the maximum number of files the file system can hold. A typical allocation heuristic for inodes in a file system is one percent of total size.
A file's inode number can be found using the ls -i command. The ls -i command prints the i-node number in the first column of the report, and a file's inode contents can be found using the stat command.