Ext2, Ext3, Ext4 file systems

Ext2, Ext3, Ext4 are default file systems for most of Linux operating systems. They are all based on the UFS (UNIX File System). Ext3 and Ext4 introduced file system journaling.

DOS partition: MBR data structures

DOS  Partition tables exist in the MBR, the special part of disk which is located in the first sector of disk drive. You can also find DOS Partition tables in the first sector of  the each extended partition.