The MBR (Master Boot Record) is a type of partitioning scheme, like GPT. Partitioning schemes are protocols for how to create disk partitions
Basically, in a bit of dedicated space at the start of a storage drive we store the boot loader code (e.g. GRUB) and a partition table, which is a data structure tracking where all the disk partitions are.
What is MBR’s role in the boot process? See Boot Process. Basically, BIOS does its thing, then transfers execution to the boot loader code.
In the context of installing operating systems, you should know these details:
- MBR supports a maximum of 4 primary partitions.
- Each partition is limited in size to 2TB.
Interesting note: there exists extremely destructive malware that can wipe the MBR’s contents, making a system basically irrecoverable. It’s been used by Russia against Ukraine in 2022.