A “volume” is roughly the same as a partition. This is because in a RAID (redundant array of inexpensive drives), multiple partitions from different hard disk drives make up a logical volume. The same applies in a system that utilizes LVM (logical volume management). RAID and LVM are out of the scope of this module. The curious are encouraged to look up these mechanisms and at least understand why they are useful.
What is important is that a volume can also be seen as an array of sectors. However, a volume does not contain files, only sectors. In order to create the illustion of files from sectors of a volume, we need a file system.