While candy, greeting cards, flowers or an evening out have been the clear choice to mark the annual celebration of love, the historical origins of Valentine’s Day are a lot more murky.

According to the Encyclopædia Britannica, the holiday’s origins come from the Roman spring festival of Lupercalia, which was replaced by St. Valentine’s Day in the 5th century and came to be celebrated as a day of romance in the 14th century.

Legend has it that a martyred priest bearing the name St. Valentine signed a letter “from your Valentine” to his jailer’s daughter while imprisoned. Other accounts credit the naming of the day for different saints, although, it is possible they might have been the same individual.

Another common legend, the encyclopedia states, is the saint defied his emperor’s orders and secretly married couples to spare the husbands from war — which is the reason why the holiday is associated with love.

Today, however, the holiday has expanded beyond lovers, with people celebrating it with their friends, coworkers and pets.