Types

• Any hard drive that has been partitioned will have an MBR, and its primary function is to locate the other common boot sector type, a volume boot record. Once accessed, the VBR is responsible for starting up and running the operating system of the computer.
  
  

Identification

• A boot sector is always located at the first part of a disc and will always contain the same executable instructions. This is how the BIOS locates and identifies the boot sector of a disc.
  
  

Corruption

• A computer's BIOS, which is the firmware for the motherboard, looks for the boot sector of a disk when it is first turned on. If a boot sector becomes corrupt or is attacked by a virus, then the BIOS cannot recognize the boot sector and the operating system will be unable to load. Many viruses attack boot sectors because of this reason.
  
  

Viruses

• Because your computer cannot boot properly without a boot sector, a virus that attacks a boot sector can be especially devastating. There are tools to remove viruses from boot sectors, but the process can be complicated.
  
  

Warning

• Boot sectors must meet a very strict set of criteria in order to work properly. Editing a boot sector is not recommended unless it has become corrupt or is infected by a virus.