Today, Valentine's Day has little religious significance. But the holiday actually commemorates a priest, St. Valentine, who married young couples in secret around 270 AD.
At that time, Roman Emperor Claudius II outlawed marriages involving younger citizens, claiming that "married men made poor soldiers," according to the BBC.
There are many legends about St. Valentine — one of the most popular being that the saint fell in love with the jailer's daughter while imprisoned. Before he was beheaded, the Christian martyr wrote his sweetheart a farewell letter signed, "From your Valentine."
To many people Valentine's Day means boxes of chocolate, bouquets of flowers and bundles of balloons. Others celebrate with underwater weddings in London, chocolate spas in Japan and decorated apples in Iraq.