The blackjack shoe is an invention bought into land-based casinos back in the 1960s. Today, you'll find that every casino, whether online or land-based, will feature some sort of shoe. This can be either automatic or manual. By making use of these card shuffling machines, it makes the job of counting cards in blackjack totally redundant. With up to 8 decks being constantly added to the shoe, and with many being replaced before a complete deck is dealt out, the card counter has no hope.
There are many ways that you an gain an upper hand when playing blackjack at the land based casino. They all fall under the title of advantage play. Essentially, you're finding ways to beat the casino's fixed advantage, also known as the house edge. The most well known method is card counting, though this is less relevant today than it was 20 years ago. Then there are things like trying to spot the dealers down card or marking the backs of the cards themselves. Finally, we have plain cheating.