Learning about inodes

Yesterday I watched again Antitrust, but now in HD 720p to better see the commands he used :) He was playing with inodes to restore removed data and I became curious, because I heard and saw inodes, but never knew what are they.
For me useful info was at http://www.linfo.org/inode.html and http://www.cyberciti.biz/tips/understanding-unixlinux-filesystem-inodes.html I didn't know about the command stat:

mike@mikembp:~$ stat -x /etc/php.ini
  File: "/etc/php.ini"
  Size: 70183        FileType: Regular File
  Mode: (0644/-rw-r--r--)         Uid: (    0/    root)  Gid: (    0/   wheel)
Device: 1,2   Inode: 26362462    Links: 1
Access: Mon Feb  3 14:44:46 2014
Modify: Mon Feb  3 14:44:46 2014
Change: Mon Feb  3 14:44:46 2014

mike@mikembp:~$ stat -x /Users/mike/
  File: "/Users/mike/"
  Size: 2958         FileType: Directory
  Mode: (0755/drwxr-xr-x)         Uid: (  501/    mike)  Gid: (   20/   staff)
Device: 1,2   Inode: 326834    Links: 87
Access: Sat May 18 08:22:51 2013
Modify: Fri Feb 21 07:40:46 2014
Change: Fri Feb 21 07:40:46 2014