I just learned about inode's yesterday.
The inode identifies the file and it's attributes.
An inode in a data structure on a traditional Unix-style file system such as UFS or ext 3.
An inode stores basic information about a regular file, directory or other file system object.
You can use the ls -i command to see the inode # of the file.
This is just a sample:
I found this article with a Google search "Linux File System"