What is 'inode'?
All UNIX files have its description kept in a structure called 'inode'. The inode have info about the file-size, its location, time of last access, time of last modification, permission and so on. Directories are also shown as files and have an associated inode. In addition to descriptions about the file, the inode have pointers to the data blocks of the file. If the file is large, inode has indirect pointer to a block of pointers to additional data blocks (this further aggregates for larger files). A block is typically 8k.
Inode having of the following fields:
File owner identifier
File access permissions
File access times
File type
Number of links
File size
Location of the file data