A volume boot record is a type of boot sector

Boot sector

A boot sector or boot block is a region of a hard disk, floppy disk, optical disc, or other data storage device that contains machine code to be loaded into random-access memory by a computer system's built-in firmware...

 introduced by the IBM Personal Computer. It may be found on a partitioned

Disk partitioning

Disk partitioning is the act of dividing a hard disk drive into multiple logical storage units referred to as partitions, to treat one physical disk drive as if it were multiple disks. Partitions are also termed "slices" for operating systems based on BSD, Solaris or GNU Hurd...

 data storage device

Data storage device

thumb|200px|right|A reel-to-reel tape recorder .The magnetic tape is a data storage medium. The recorder is data storage equipment using a portable medium to store the data....

 such as a hard disk

Hard disk

A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...

, or an unpartitioned device such as a floppy disk

Floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

, and contains machine code

Machine code

Machine code or machine language is a system of impartible instructions executed directly by a computer's central processing unit. Each instruction performs a very specific task, typically either an operation on a unit of data Machine code or machine language is a system of impartible instructions...

 for bootstrapping program

Computer program

A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...

s (usually, but not necessarily, operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

s) stored in other parts of the device. On non-partitioned storage devices, it is the first sector of the device. On partitioned devices, it is the first sector

Disk sector

In computer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. Each sector stores a fixed amount of user data. Traditional formatting of these storage media provides space for 512 bytes or 2048 bytes of user-accessible data per sector...

 of an individual partition on the device, with the first sector of the entire device being a master boot record

Master boot record

A master boot record is a type of boot sector popularized by the IBM Personal Computer. It consists of a sequence of 512 bytes located at the first sector of a data storage device such as a hard disk...

 (MBR) containing the partition table.

The code in volume boot records is invoked either directly by the machine's firmware or indirectly by code in the master boot record or a boot manager. Code in the MBR and VBR is in essence loaded the same way.

Invoking a VBR via a boot manager is known as chain loading

Chain loading

Chain loading is a method used by computer programs to replace the currently executing program with a new program, using a common data area to pass information from the current program to the new program. It occurs in several areas of computing.Chain loading is similar to the use of overlays...

. Some dual boot

Dual boot

Multi-boot or Multi-booting is the act of installing multiple operating systems on a computer, and being able to choose which one to boot when starting the computer. The term dual-booting refers to the common configuration of exactly two operating systems...

 systems, such as NTLDR

NTLDR

NTLDR is the boot loader for all releases of Windows NT operating system up to and including Windows XP and Windows Server 2003. NTLDR is typically run from the primary hard disk drive, but it can also run from portable storage devices such as a CD-ROM, USB flash drive, or floppy disk...

 (the boot loader for all releases of Microsoft's Windows NT-derived operating systems up to and including Windows XP

Windows XP

Windows XP is an operating system produced by Microsoft for use on personal computers, including home and business desktops, laptops and media centers. First released to computer manufacturers on August 24, 2001, it is the second most popular version of Windows, based on installed user base...

 and Windows Server 2003

Windows Server 2003

Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...

), take copies of the bootstrap code that individual operating systems install into a single partition's VBR and store them in disc files, loading the relevant VBR content from file after the boot loader has asked the user which operating system to bootstrap.
In Windows Vista

Windows Vista

Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

, Windows Server 2008 and newer versions, NTLDR was replaced; the boot loader functionality is instead provided by two new components: winload.exe and the Windows Boot Manager.

In file system

File system

A file system is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device which contain it. A file system organizes data in an efficient manner and is tuned to the...

s such as FAT

File Allocation Table

File Allocation Table is a computer file system architecture now widely used on many computer systems and most memory cards, such as those used with digital cameras. FAT file systems are commonly found on floppy disks, flash memory cards, digital cameras, and many other portable devices because of...

 and NTFS

NTFS

NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, Windows Vista, and Windows 7....

, the VBR also contains a BIOS parameter block

BIOS parameter block

In computing, the BIOS parameter block, often shortened to BPB, is a data structure in the Volume Boot Record describing the physical layout of a data storage volume. On partitioned devices, such as hard disks, the BPB describes the volume partition, whereas, on unpartitioned devices, such as...

that specifies the location and layout of the principal on-disc data structures for the file system.