Light crude - Definition

Light crude as opposed to heavy crude contains a low content of wax. The clear cut definition of 'light' and 'heavy' crude is hard to find, simply because the classification so made is based more on practical grounds than theoretical. Since crudes with high viscosities are more difficult to transport/pump, those with apparently lighter wax content are referred to as 'light crude' and the ones with substantially more wax are classified as 'heavy crude'.