• A method of organizing blocks on a storage device into files and directories.
• A data structure that translates the physical view of a disc into a logical structure.
• The way in which file s are named and where they are placed logically for storage and retrieval.

What Is BTRFS ?

• Next Gen. File system for Linux 
• Also called “BUTTER FS” or “BETTER FS” 
• Motivated from zfs of Solaris 
• Support for copy on write
• Unlike zfs which is licensed under CDDL(Common Development and Distribution License), Btrfs is GPL licensed
• Only test versions are released(accepted in 2.6.29)
• It have lots and lots of features compared to extended series