Generally, file systems are referred to as the collections of files, which include information related to those files. It would be impossible to tell where one piece of data stops and the next begins without a file system. There are four blocks in a file system: 

• Super Block: A superblock CONTAINS information about a file system, including block size, group size, USAGE statistics, empty/filled blocks, inode table size & location, and so on. One of the tools used to describe a file system, along with inodes, entries, and files, is the superblock. Multiple superblocks are CREATED with the file system, as the superblock contains critical information.  
• Boot Block: Located on the disk label, a boot block is a special set of blocks that contains data or information on the disk layout. Normally, this block contains the bootstrap loader program, which a user runs upon LAUNCHING the host computer. The boot block remains blank if the file system is not used for boot.    
• Data Block: Also called storage blocks, data blocks contain the remainder of the space allocated to the file system. The data block's size is measured at the time of file system creation. For a regular file, the CONTENT of files is contained in the data blocks. For directories, the inode number and file name of the files are contained in the data blocks.  
• Inode: Inodes contain information about each file in the filesystem. Normally, an inode doesn't contain a file's name, which is located in a directory instead.  An inode contains information such as the type of file, the permission bits, the owner, the group, the file size, and the time when the file was modified.