Windows Partitions

The Windows operating system requires various partitions for normal operation. This article explains which partitions are automatically selected when selecting 'Create an image of the partition(s) required to backup and restore Windows'.


UEFI booting systems with GPT-style disks

Introduced with Windows 8.0 and a few Windows 7 systems, GPT disks are the replacement for the legacy MBR disk format. GPT disks can have up to 128 partitions and have a maximum size of 9.4 ZB (9.4 × 1021 bytes)

https://en.wikipedia.org/wiki/GUID_Partition_Table

Partition
Unique Identifier
Description
Windows Recovery de94bba4-06d1-4d40-a16a-bfd50179d6ac There may be more than one Recovery Partitions:
Windows RE Tools
 - Provides the 'Startup Repair' options for Windows recovery.
Recovery Image - There may also be an additional manufacturer system recovery partition.

EFI System partition (ESP)

c12a7328-f81f-11d2-ba4b-00a0c93ec93b Always formatted FAT32 and between 200 and 300 MB in size, this partition contains the boot loader that runs when the system starts. The critical files in here are the Boot Configuration Data (BCD) and the EFI micro-code.
Microsoft Reserved Partition (MSR) e3c9e316-0b5c-4db8-817d-f92df00215ae Usually 128 MB in size, this unformatted partition is reserved for MS data structures including the Logical Disk Manager (LDM) for dynamic disks. Every GPT disk initialized by Windows includes this partition.
Operating System (Windows C:) ebd0a0a2-b9e5-4433-87c0-68b6b72699c7 Always formatted using NTFS, this partition contains the full Windows Operating System and is loaded using the BCD in the ESP,
Note: The Microsoft Reserved Partition (MSR) is not shown in the Windows Disk Management Console

Surface Pro 3 running Windows 10


Legacy MBR booting systems

MBR systems support a maximum disk size of 2TB and up to four primary partitions. In modern PCs this format has been superseded by the more flexible GPT disk format.

https://en.wikipedia.org/wiki/Master_boot_record

Partition
Description
Microsoft Reserved Partition (MSR)

For MBR disks, Windows 7 onwards, this is the 'Active' partition and contains the Boot Configuration Data (BCD). This partition provides the second stage for the MBR boot process after the MBR boot code. 

Windows XP and Vista do not use this partition.

Operating System (Windows C:) This partition contains the full Windows Operating System.
For Windows XP & Vista this is the 'Active' partition and is the only partition required to boot and start Windows.
WinRE Tools Partition Windows 10 includes this small partition, usually located immediately after the Windows partition, to provides the 'Startup Repair' options for Windows recovery and to store the WinRE image file. 

MBR systems may also contain proprietary system recovery partitions, however, there are no unique identifiers for these partitions and they are not automatically included.

Windows 7 MBR System

Windows 10 MBR System