A storage device is exposed as a block device, such as /dev/sda or /dev/nvme0n1. It can contain a partition table, whose entries describe regions exposed as child block devices. A partition can then hold a filesystem, swap signature, RAID member, encryption container, logical-volume physical volume, or another data format.
The Filesystem · Lesson 3
Anatomy of a Disk
Learn how block devices, partition tables, partitions, and filesystems form distinct storage layers.