Valentine’s Day (St. Valentine’s Day) was originally meant to celebrate St.Valentine.

St. Valentine performed weddings for soldiers who were not allowed to marry. Valentine was put in prison for this. Before Valentine was executed, he wrote a letter to the daughter of his jailer, which he signed “From your valentine.” St. Valentine was buried on February 14. However, Valentine’s Day was not associated with love and romance until the Middle Ages.

Source: http://www.infoplease.com/spot/valentinesdayhistory.html