Saint Valentine's Day, commonly shortened to Valentine's Day, is an annual commemoration held on February 14 celebrating love and affection between intimate companions. The day is named after one or more early Christian martyrs, Saint Valentine, and was established by Pope Gelasius I in 496 AD. It is traditionally a day on which lovers express their love for each other by presenting flowers, offering confectionery, and sending greeting cards (known as "valentines").
Modern Valentine's Day symbols include the heart-shaped outline, doves, and the figure of the winged Cupid. Since the 19th century, handwritten valentines have given way to mass-produced greeting cards (wikipedia.org)
Valentine greetings have been popular since the Middle Ages, a time when prospective lovers said or sang their romantic verses. Written valentines began to appear after 1400. Paper valentines originated in the 1500s, being exchanged in Europe and being given in place of valentine gifts and oral or musical valentine greetings. They were particularly popular in England. The first written valentine (formerly known as "poetical or amorous addresses") is traditionally attributed to the imprisoned Charles, Duke of Orleans, in 1415. While confined in the Tower of London after the Battle of Agincourt, the young Duke reportedly passed his time by writing romantic verses for his wife in France. Approximately sixty of the Duke's poems remain and can be seen among the royal papers in the British Museum. They are credited with being the first modern day valentines.