Black flags adorned with skulls and crossbones are known as Jolly Roger flags. Jolly Roger is the traditional English name for the flags flown to identify a pirate ship about to attack during the early 18th century. The French pirates flew a blood red flag instead of the black flags. The French described this flag as, Jolie Rouge, which translated meant "pretty or fine red". Thus, jolie rouge drapeau, which translated means pretty red flag, or fine red flag. This is how the Jolly Roger originated, it was simply a play on the French words jolie rouge.
The flag was meant to announce a pirate’s presence, and quickly convey their intent to ships in their path. Despite its appearance in popular culture, plain black flags were often used by pirates in the 17th-18th century. Historically, the flag was flown to frighten pirates' victims into surrendering without a fight. The early flags were painted on sail cloth by the crew members, or sometimes fabricated from scraps of sail cloth sewn together. Later in the Golden Age of Piracy, the flags became more elaborate and sophisticated. It’s a flag of power that has good branding power on its side to this day.