The barber pole’s colors are a legacy of a (thankfully) long-gone era when people went to barbers not just for a haircut or shave but also for bloodletting and other medical procedures. During the Middle Ages bloodletting, which involves cutting open a vein and allowing blood to drain, was a common treatment for a wide range of maladies, from sore throat to plague. Monks, who often cared for the sick, performed the procedure, and barbers, given their skill with sharp instruments, sometimes provided assistance. After Pope Alexander III in 1163 prohibited clergymen from carrying out the procedure, barbers added bloodletting—something physicians of the day considered necessary but too menial to do themselves–to their repertoires. Known as barber-surgeons, they also took on such tasks as pulling teeth, setting bones and treating wounds. Ambroise Pare, a 16th-century Frenchman considered the father of modern surgery, started his career as a barber-surgeon.

The look of the barber pole is linked to bloodletting, with red representing blood and white representing the bandages used to stem the bleeding. The pole itself is said to symbolize the stick that a patient squeezed to make the veins in his arm stand out more prominently for the procedure. In Europe, barber poles traditionally are red and white, while in America, the poles are red, white and blue. One theory holds that blue is symbolic of the veins cut during bloodletting, while another interpretation suggests blue was added to the pole as a show of patriotism and a nod to the nation’s flag.

By the mid-1500s, English barbers were banned from providing surgical treatments, although they could continue extracting teeth. Both barbers and surgeons, however, remained part of the same trade guild until 1745. While bloodletting largely fell out of favor with the medical community in the 19th century, it’s still used today to treat a small number of conditions.