How a Halloween?

How did Halloween evolve as a holiday into what it is today? For those of you who aren’t familiar with the specifics of the American holiday (particularly as it is in America), children dress up in costumes and go door-to-door threatening the occupiers with harm unless given candy. No, that’s not the exact tone, but it is effectively what happens. Masked children, often in large groups, occasionally wielding an imitation firearm or sword, rove through neighbourhoods demanding sweets from those citizens foolish enough to open the door to their brigandage. Surely, that’s what ‘Trick or treat’ means!