Many computer users are familiar with the basic idea of filesystems. A storage device is divided into partitions each formatted to a particular filesystem that holds files. Well, just as the filesystem hold the files, a partition table holds the filesystems. There are a few partition table types. The most commonly known one is MBR. Master Boot Record (MBR) - Most IBM-based PC storage units use this partition table format. MBR is often referred to as the msdos partition table. The MBR can only support storage devices up to two terabytes. MBR supports the concept of logical and primary partitions. A storage unit with the MBR table can only have up to four primary partitions. Many users wanting to make a multiboot system with more than four Linux distros often have the problem of not being able to support more partitions. Remember, logical partitions cannot be made bootable. Multiboot systems must use a different partition table discussed later. GUID Partition Table (GPT) - Some IBM-based PC storage units have GPT, although it is usually because the user reformatted from MBR to GPT. However, most Intel-based Mac systems use GPT by default. The GPT partition table offers many improvements over MBR. GPT can support storage units up to over nine zettabytes. GPT is also the most highly recommended partition table for computers needing more than four operating systems on one hard-drive. For example, if a computer with a ten terabyte hard-disk is meant to be a multiboot system for seven different Linux distros, then GPT should be used. Most Unix and Unix-like operating systems can fully support GPT. However, most Windows systems cannot run on a GPT partition table. As for Mac systems, only the Intel-based ones can boot from GPT. Apple Partition Map (APM) - The PowerPC-based Mac systems can only boot from APM partition tables. This is usually referred to as the Mac or Apple partition table. Linux and Intel-based Macs can use APM. Windows does not support APM. Amiga rigid disk block (RDB) - Amiga systems use the RDB partition table. These partition tables support up to about 4*10^19TB. That is forty quintillion terabytes. AIX – The AIX partition table is used by proprietary AIX systems. By default, Linux does not natively support the AIX partition table. BSD – BSD Unix systems can use the BSD partition table. Linux and Windows cannot read BSD partition tables. Others - Some other partition table formats are listed below. The below listed are very rarely used. Not much information can be seen on the Internet about them. dvh humax pc98 sgi sun Removable Storage - You may be wondering, "Which partition table do flash drives, SD cards, etc. use?". Well, since all systems can at least read MBR, the majority of mobile/removable storage uses MBR. Formatting the partition table - To change or reformat a partition table, use Gparted and click "Device > Create Partition Table". Then, choose the desired partition table. Alternately, Parted can be used to format a storage device with a particular partitioning table (also called a "disk-label"). Doing so will erase all partitions and data on the selected storage device. The command is "parted mklabel DISKLABEL". The command requires Root privileges. The user will need to create new partitions for the storage device. Supported partitioning tables (supported by parted) include the listed below. bsd loop (raw disk access) gpt mac (Apple Partition Map (APM)) msdos (commonly called MBR) pc98 sun WARNING: Changing the partition table will erase the filesystems, partitions, and files. This is a more “low-level” format. However, the files are not truly gone. Read http://www.linux.org/threads/undelete-files-on-linux-systems.4316/ to fully understand the “deletion” of files. You may also be wondering which is the best one for you. Well, use MBR with Windows and mobile systems (like Android), APM on PowerPC Macs and iOS, RDB on Amiga, and GPT on all other systems. However, you may have specific reasons for placing an OS on a different partition table than what is recommended one sentence previous.