To play bridge you need four people sitting at a table and a deck of cards. One person (the dealer), distributes thirteen cards to each player, one at a time, in a clockwise direction. There are fifty two cards in the deck, and four suits (Spades ♠, Hearts ♥, Diamonds ♦ Clubs ♣). The Ace is the highest, followed by the King, etc, down to the two. That’s AKQJ1098765432.
The four players, in two partnerships, score points by winning tricks. A trick is four cards, played one at a time, clockwise. The highest card wins. Thirteen tricks may be taken on each hand. One person leads, and everyone must follow suit, provided they were dealt a card of that suit. Whoever wins the trick starts the play to the next trick, and leads whatever card they choose. The aim is to fulfil a contract (an undertaking to win a certain number of tricks) which one partnership has made.
A hand may be played in no trumps or with any trump suit: Spades ♠, or Hearts ♥, or Diamonds ♦, Clubs ♣. In no trumps, the highest card led to any trick wins. But a trump will beat any card, provided you have no cards left in the suit led.
When a partnership holds the majority of cards (eight or more) in any one suit, it’s said there's a “fit”. To evaluate how good your hand is, add up your high card points (i.e. honour cards, Aces, Kings, Queens and Jacks) and long suit points.
High Card Points - 4 for each Ace, 3 for each King, 2 for each Queen, and 1 for each Jack over the whole hand. ♠ AK1086 ♥ QJ105♦106 ♣AQ This hand has 16 high card points.
Length Points 1 point for any card in a suit longer than four. ♠ AK1086 ♥ QJ105♦106 ♣AQ This hand has 1 extra length point of the fifth spade. So the total here is 16 high, and 1 length for the fifth spade = 17 total points.
Usually, but not always, the partnership with more points makes a contract for a certain number of tricks, in either no tumps or one of the four suits. They become the declaring side. If they succeed, and take the tricks (or more) that they contracted for, they gain points. If they don't make their contract, the other side, called the defending side, scores points for the number of tricks by which they were short.