Here's an example of a little-used unit of volume: the cubic centimeter. Here, it is clearly written as cm³. However, it has two more common equivalents: cubic centimeters — expressed using "cc," and milliliters (mL). Other liquid products throughout most supermarkets use mL as their metric measurement of volume, though cc and cm³ are one-to-one equivalents. Why not just use mL then? I guess they would answer with something similar to what Abe Simpson once said:
“My car gets forty rods to the hogshead, and that’s the way I likes it!”
