Within Disk Utility, the hard drive or SSD is referred to as a "disk". It is represented in the
list of drives on the left side of the window, usually by a silver or yellow hard drive icon. Note
that icons representing the physical device are never indented in the list.
The named, logical space that is set aside within the disk is called a "volume". A volume is also
represented by hard drive icons, but they are indented beneath the disk where they are stored. Shown
at right, the items named Snow Leopard, Lion, Mountain Lion, Mavericks, and Yosemite are all examples
of volumes found within the disk listed as "256.06 GB SanDisk SSD." Unlike volume names, disk names
cannot easily be modified; they are set at the manufacturing facility.
Every disk used with OS X needs to be "partitioned" with one or more volumes. When you partition a disk,
all of the volumes that are created are formatted as part of the process. That is what we'll be doing.
Please note that Apple's Disk Utility has remained virtually unchanged from OS X 10.6 thru OS X 10.10. While
this document shows screenshots from OS X 10.10, the options shown are available in earlier versions
of the OS going back to 10.6. Earlier versions of OS X account for a tiny fraction of users and are
not covered in this document, but the process is very similar.