Updated: 09/12/2023 by Computer Hope
Hard drive stack

With a computer hard drive, a disk partition or partition is a section of the hard drive that is separated from other segments. Partitions enable users to divide a physical disk into logical sections. For example, allowing multiple operating systems to run on the same device.

With older file allocation tables, such as FAT (file allocation table) 16, creating smaller partitions allows a computer hard drive to run more efficiently and save more disk space. However, this is no longer the case with new file allocation tables like FAT32.

Which drive is the first partition?

On Microsoft Windows computers, by default, the first drive (disk 0 or drive 0) containing the first partition is the C: drive.

What does a partition look like?

The best way to see what a partition looks like is to open the disk management tool.

Press the Windows key, type Disk Management, and press Enter.


A small amount of disk space allocated to a partition is unusable space and cannot store data. For example, the picture below shows the Extra Volume (E:) drive, or partition, having a capacity of 5.86 GB, but the Free Space available for storing data is only 5.84 GB. The 20 MB (.02 GB) difference is unusable space.

Windows Disk Management

Types of partitions

There are also several partition types. Below is a listing of partitions with a brief description.


Some of these partitions may not be available in your partition utility.

Partition Description
AIX partition (boot) A partition used with the AIX (advanced interactive executive) operating system.
Apple File System (APFS) partition A partition used with Apple computers. These can be formatted as encrypted, case-sensitive, or encrypted and case-sensitive.
Boot partition As defined by Microsoft, a boot partition contains the files required for a system startup. Also see: System partition
BSD/OS partition (OpenBSD) A partition is used with the BSD (Berkeley Software Distribution) operating system.
DOS partition (12-bit, 16-bit) A partition used with older versions of MS-DOS.
DOS extended partition A partition extended from one or more of the original MS-DOS partitions.
DRDOS (hidden) A partition used with the DR. DOS operating system.
Extended partition A partition that is extended from one or more of the primary partitions.
Hibernation partition A partition used with older hibernation programs.
HPFS partition (OS/2 IFS) An HPFS (high-performance file system) partition used with IBM OS/2 and Microsoft NT 3.x
Linux (Linux native, Linux swap, Linux extended, ext2fs) A partition used with various variants of the Linux operating systems.
Mac OS Extended partition A partition for Apple computers using macOS 10.12 and earlier. These can be formatted as journaled, journaled and encrypted, case-sensitive and journaled, and case-sensitive, journaled, and encrypted.
MINIX A partition used with the MINIX operating system.
NON-DOS partition When using Microsoft fdisk, a NON-DOS partition indicates a partition is not native to the Microsoft operating system. For example, this could be a Linux partition.
NEC DOS A partition used with the old NEC DOS variant.
NEXTSTEP A partition used with the NeXTSTEP operating system.
Novell NetWare A partition used with the Novell NetWare operating system.
NTFS (NTFS file system) A partition used with Microsoft Windows NT 4.x, Windows 2000, Windows XP, and later versions.
Partition Magic (PowerQuest) A partition created using the Partition Magic utility by PowerQuest.
PC-ARMOUR A partition created by the PC ARMOUR security utility. When created, this partition is commonly protected by a password.
Primary In a Microsoft operating system, the Primary Partition refers to the main or first partition used for the Microsoft operating system.
Solaris X86 A partition used with the Sun Solaris X86 platform operating system.
System partition As defined by Microsoft, a system partition is a partition containing the system32 directory. Also see: boot partition.
Tandy DOS A partition used with the old Tandy DOS variant.
Unix System V (SCO, IRIX, ISC, Unix, UnixWare, etc...) A partition used with various Unix operating systems.
VMware (VMware Swap) A partition used by VMware.
Xenix (Xenix /usr) A partition used with the Xenix operating system.

Does a hard drive require a partition?

A hard drive must have at least one partition. The first partition on a hard drive is the primary partition, and if it's the computer's only one, it is assigned the C: drive letter. Additional partitions are only needed if you want more than one drive letter assigned to the device or need to separate the storage space into smaller segments.

Boot sector, Delpart, FAT, Hard drive terms, Hardware terms, Hidden partition, MBR, Virtual drive