At the begining St. Valentine's Day was the day for secret lovers and hidden messages. One of the legends says that Valentine was a priest that served in the third century Rome. The early pastors of Roman Christian churches used St. Valentine's Day as the day young men chose young girls to marry them.
In the United States, the first commercially printed Valentine's Day cards appeared in the early 1800s.
Nowadays St. Valentine's Day is a quite commercial day and people have forgotten the real meaning of this festivity that contains elements of ancient Roman and Christian traditions.