The term black fax refers to a prank fax transmission, consisting of one or more pages entirely filled with a uniform black tone. The sender's intention is generally to use up as much of the recipient's fax ink, toner, or thermal paper as possible, thus costing the recipient money, as well as denying the recipient use of their own machine (similar to computer-based denial of service attacks).[1][2] This is made easier because fax transmission protocols compress the solid black image very well, so a very short fax call can produce many pages.