What is celebrated each year on February 14?

Valentine’s Day

In Risk, what is the minimum army units you must leave behind in a territory after attacking? What classical composer wrote "The Magic Flute"? What famous revolt in 1381 involved English peasants challenging feudalism? What is the process of water infiltrating the ground called? In the Pokémon video game series, how many Pokémon were in the original Pokédex?