Devices, etc. - understanding distinctions among these entities is fundamental to understanding what you are partitioning when you partition, what you are formatting when you format, what you are mounting when you mount, what you are encrypting when you encrypt. People often confuse them.

Western Digital manufactures hard disks
Given a hard disk, grub manufactures a partition table
Given a partition table , fdisk manufactures a partition
Given a partition, mkfs manufactures a filesystem
Given a filesystem, vi manufactures a file