Saint Valentine's Day (commonly shortened to Valentine's Day) is an annual holiday held on February 14 celebrating love and affection between intimate companions. The holiday is named after one or more early Christian martyrs named Valentine and was established by Pope Gelasius I in AD 496. 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"). The holiday first became associated with romantic love in the circle of Geoffrey Chaucer in the High Middle Ages, when the tradition of courtly love flourished.

Numerous early Christian martyrs were named Valentine. The Valentines honored on February 14 are Valentine of Rome and Valentine of Terni. Valentine of Rome was a priest in Rome who was martyred about AD 269 and was buried on the Via Flaminia. His relics are at the Church of Saint Praxed in Rome, and at Whitefriar Street Carmelite Church in Dublin, Ireland.

Valentine of Terni became bishop of Interamna (modern Terni) about AD 197 and is said to have been martyred during the persecution under Emperor Aurelian. He is also buried on the Via Flaminia, but in a different location than Valentine of Rome. His relics are at the Basilica of Saint Valentine in Terni (Basilica di San Valentino).

The Catholic Encyclopedia also speaks of a third saint named Valentine who was mentioned in early martyrologies under date of February 14. He was martyred in Africa with a number of companions, but nothing more is known about him. No romantic elements are present in the original early medieval biographies of either of these martyrs. By the time a Saint Valentine became linked to romance in the fourteenth century, distinctions between Valentine of Rome and Valentine of Terni were utterly lost.

The sending of Valentines was a fashion in nineteenth- century Great Britain, and, in 1847, Esther Howland developed a successful business in her Worcester, Massachusetts home with hand-made Valentine cards based on British models. The popularity of Valentine cards in 19th century America, where many Valentine cards are now general greeting cards rather than declarations of love, was a harbinger of the future commercialization of holidays in the United States. It's considered one of the Hallmark holidays.

In some South American countries Valentine's Day is known as "Día del Amor y la Amistad" (Day of Love and Friendship). For example Mexico, Costa-Rica, Ecuador, y El Salvador. Although it is similar to the United States' version in many ways, it is also common to see people do "acts of appreciation" for their friends.

In Chinese culture, there is an older observance related to lovers, called "The Night of Sevens" (Chinese: ; pinyin: Qi Xi). According to the legend, the Cowherd star and the Weaver Maid star are normally separated by the milky way (silvery river) but are allowed to meet by crossing it on the 7th day of the 7th month of the Chinese calendar. In Japan, a slightly different version of called Tanabata has been celebrated for centuries, on July 7 (Gregorian calendar). It has been considered by Westerners as similar to St. Valentine's Day[52], but it's not related to it, and its origins are completely different.

In Saudi Arabia, in 2002 and 2008, religious police banned the sale of all Valentine's Day items, telling shop workers to remove any red items, as the day is considered a Christian holiday. In 2008 this ban created a black market of roses and wrapping paper.

The Jamaat-e-Islami political party has called for the banning of the holiday. Despite this, the celebration is increasingly popular and the florist shops expect to sell great amount of flowers, especially red roses.