Short answers, pulled from the story.
Valentine of Rome was a priest in Rome who was martyred in 269 and buried on the Via Flaminia. The Feast of Saint Valentine was recorded in the 8th-century Gelasian Sacramentary on February 14. His connection to romantic love developed later, primarily through 14th-century poetry such as Geoffrey Chaucer's Parliament of Fowls.
The Parliament of Fowls (1382) by Geoffrey Chaucer is widely regarded as the first recorded association of Saint Valentine's Day with romantic love. Chaucer wrote it to honor the first anniversary of the engagement of King Richard II of England to Anne of Bohemia, both fifteen years old at the time.
Esther Howland (1828-1904) of Worcester, Massachusetts, produced and sold the first mass-produced valentines of embossed paper lace in the United States shortly after 1847. She took her inspiration from an English Valentine received from a business associate of her father and built her business by importing paper lace and floral decorations from England.
The U.S. Greeting Card Association estimates approximately 190 million valentines are sent each year in the United States. When cards exchanged in school activities are included, the figure rises to around 1 billion, making teachers the single group receiving the most valentines.
In Japan, the custom that only women give chocolates to men developed from a translation error by a chocolate-company executive during the initial promotional campaigns of the 1950s. Morozoff Ltd. first introduced the holiday in Japan in 1936. Japanese chocolate companies make roughly half their annual sales during the Valentine's Day season.
In several countries, Valentine's Day has been restricted on religious or cultural grounds. Saudi Arabia banned Valentine's Day items in 2002 and 2008, and in 2012 more than 140 Muslims were arrested for celebrating the holiday. In Iran, giving Valentine's Day gifts has been banned since 2009, with the Law Enforcement Force prosecuting distributors of related goods. In India, Hindu and Islamic traditionalists have characterized the holiday as Western cultural contamination.