The short answer: the house draws their cards after the players. This is where they get their edge. Casinos will also fatten up the house edge with side bets, by offering insurance (or even money depending on where you're playing, using more decks of cards, and game variations like standing or hitting on soft 17.

All cards are at face value, except for the King, Queen and Jack which count as 10. An Ace will have a value of 11 unless that would give a player or the dealer a score in excess of 21; in which case, it has a value of 1. The dealer starts the game. Every player gets 2 cards, face up.