Shuffle
To shuffle is to mix the cards before a hand, so that their order is random. The dealer shuffles the deck before every deal.
The simple explanation
Before each hand, the deck is mixed. A common way is the riffle shuffle: the dealer splits the deck and lets the cards fall together.
A closer look
Good shuffling makes it impossible to know the order of the cards. Many rooms use a wash, several riffles and a cut. Casinos also use automatic shufflers. A poor shuffle can be an advantage to a cheater, so players watch the dealer's work.
A practical example
The dealer shuffles the deck three times and offers it for a cut.
Full explanation
To shuffle is to mix the cards before a hand, so that their order is random. The dealer shuffles the deck before every deal.
To shuffle is to mix the cards.
It makes the order random.
A cut follows the shuffle.
Casinos may use machines.