The older BIOS (Basic Input/Output System) and its present day replacement UEFI (Unified Extensible Firmware Interface) can both be visible as the "firmware" of your laptop.
(Image : Google )
They are saved without delay at the mainboard and are the first software program this is run on your computer whilst it is powered on. Their foremost job is to initialize all connected hardware and load the real running gadget's (e.G. Ubuntu or Windows) boot loader (e.G. GRUB) from the tough disk, which then starts the OS.
Most UEFI structures additionally support CSM (Compatibility Support Module) booting, which emulates a Legacy BIOS interface.
While Legacy BIOS boot honestly and stupidly reads and executes code from a fixed address off the disk (part of the Master Boot Record), UEFI boot searches for EFI boot documents in an EFI gadget partition and executes one of those.
The older MBR (Master Boot Record) and more moderen GPT (GUID Partition Table; GUID = Global Unique Identifier) are partition table codecs.
Your tough disk is partitioned in both of those formats. The older MBR format allows simplest four number one partitions at the complete disk (although certainly one of them may be used as prolonged partition and incorporate many logical volumes), whereas GPT doesn't have this restrict and additionally helps large disks.
GPT partitioned disks might also comprise a hybrid MBR with boot code able to load the EFI files for you to aid both UEFI and Legacy BIOS boot modes.