Taking down the pot early

Say you raise preflop with AK. You get one or two callers and the flop comes K74 rainbow. You bet say a 2/3 to a full pot. Both calls. Why did the villains called the preflop raise in the first place? Do they call every raise or only when they have something good? Why did they call you on the flop? Do you almost always c-bet on the flop or do you only bet when you hit something? What type of hands would the villains call the flop bet with? Would they raise with two pair or more, would they raise a draw? Would...
Original article from http://www.articleactive.com/Article/62785/62785