The traditions of Valentine's Day date back to ancient Roman times. The Romans celebrated the feast of Lupercalia from February 13 to 15 yearly, including a matchmaking lottery in the festivities. In the fifth century, the Pope combined Saint Valentine's Day with the feast of Lupercalia and made it a day of fertility and love.
The tradition of written Valentine's Day cards began after 1400. The oldest written Valentine's Day greeting still in existence today dates back to 1415. It was written by the Duke of Orleans to his wife while he was imprisoned in the Tower of London. King Henry V also allegedly sent a Valentine written by a hired writer to Catherine of Valois.
Valentine's Day gained worldwide popularity in the 17th century. By this time it was a widespread practice for friends and lovers to send each other handwritten Valentine's Day cards and tokens of their affection. By 1900, printed cards began to gain popularity following major advances in large-scale printing technology.