What is a citation or comment at the bottom of a page called?

Which "A Christmas Carol" curmudgeon says "Bah! Humbug!"? On the U.S. West Coast, what does the time zone abbreviation PST stand for? A cinerary urn is a container for what remains of the dead? A cinquain is a poem consisting of how many lines? A city and an island in British Columbia are named for which sea captain who explored the area in 1792? In which city is the Shakespeare play set in which a character asks "What news on the Rialto?" A civil what might design dams, bridges and highways? Which civil rights group, founded in 1942, shares its acronym with the part of an apple where the seeds are?