From Wikipedia:

Disk partitioning or disk slicing is the creation of one or more regions on secondary storage, so that each region can be managed separately.

An entire disk may be allocated to a single partition, or multiple ones for cases such as dual-booting, maintaining a swap partition, or to logically separate data such as audio and video files. The partitioning scheme is stored in a partition table such as Master Boot Record (MBR) or GUID Partition Table (GPT).

EFI system partition - ArchWiki