A Question on inode - ext3FS

["lakshmi pathi" <lakshmipathi g gmail com>]

I have noticed that whenever you edit a file content,a new inode
number is assigned with the File.
But Sometime file changes the inode number,Sometimes it remains as older inode.

Can anyone please let know the concept behind this - modifing content
changes the file's inode but not all the time?

I'm using Fedora 7  with ext3 file system. (Kernel : 2.6.25.4)

Cheers,
Lakshmipathi.G