Difference among UEFI, BIOS, GPT, MBR

UEFI means Unified Extensible Firmware Interface. It is the successor to EFI, which stands for  Extensible Firmware Interface. During 1995, Intel realized that the IBM BIOS (Basic Input/output System) style firmware interface had many inconvinient limitations. These limitations didn’t really affect the average users, but they made it very arduous to produce high-performance servers, namely. As a result, Intel started developing the EFI in 1998. In 2005, Intel ceased development of the EFI  and contributed it to the Unified EFI Forum . Intel still continues to license the EFI specification , but the UEFI specification is owned by the Forum. The advantages of UEFI over BIOS is very high, a few notable ones are: 

 A powerful pre-boot environment capable of running many applications -

• CPU-independent architecture ( ARM Arch32, Arm Arch64, Itanium, x86, x64)
• legacy booting and BIOS interface compatibility
• Dependable ability to boot from disks larger than 2TiB (not Terabyte)

If you want to organize and keep track of partitions on a disk, whether you are using HDD or an SSD, you need what’s known as a partition table, such as GPT (GUID Partition Table) and  MBR (Master Boot Record). A legacy BIOS system is only able to boot from MBR partition tables (there are some exceptions) and the MBR specification can merely address up to 2TiB of disk space, which results in a BIOS system being able to boot from disks of 2TiB or lesser.

Other disadvantages of MBR formatted disks include a limited bootable partitions and boot manager. MBR only uses a one sector of the disk for its data, called the boot sector which is the root cause of these problems.

Again, disappointed with the BIOS and MBR booting , Intel developed  GPT specifications to remedy the shortcomings of the available options. The GPT specification allowed the disks of significantly hugeee size (up to Zettabytes in size) just for partition addressing, 64B instead of the 16B used by MBR. Due to GPT addressing sectors as opposed to individual bits or bytes GPT can partition disks of varying sizes depending on the sector size.

 

One has to make Petabyte and Exabyte disks before one can think of reaching the GPT partition addressing limitation. Boot code and partition table are also separate in GPT.

The signing of the executable files is called Secure Boot . If the signature matches a signature that has been previously registered with the UEFI firmware, then the motherboard will allow it to boot. 

Well there you have it the basic Difference among UEFI, BIOS, GPT, MBR .You can dig up more in wikipedia .Be sure to comment and share ;) .