Players play cards from their hand to the table in a series of rounds, or “tricks” which are each evaluated separately to determine a winner and to apply other potential effects.
The most common way to win a trick is by having the card with highest value of the suit that was led, but many classical card games use the “trump” system (where the certain cards, usually those of a designated suit, will win the trick if they are played.) Occasionally there is a round of bidding to determine this trump suit.
In many trick taking games (though not all), players are required to “follow suit”, i.e. play a card of the same suit as was led if they have one. If they do not have a matching card, they must play another card from their hand.
Cards are played sequentially, not simultaneously.