A slot is a dynamic placeholder that waits for (passive) or calls out for content (active). A slot can contain content that is delivered to the page by either a scenario using an Add to Slot action or by a targeter. Several slot properties are important to understand for offer management.

Until the 1990s, in live casinos and online, players dropped coins into slots to activate games for each spin. Later, bill validators and credit meters replaced slots. Then came video slots that could have hundreds of paylines, multiple bonus features and jackpot levels.

On most machines, a coin or paper ticket with a barcode is inserted into the slot, or the player pushes a lever or button to activate the reels. When a winning combination of symbols appears, the machine awards credits according to the paytable. Symbols vary by machine and can include fruits, bells and stylized lucky sevens.

Once the RNG generates a sequence of three numbers, the computer uses an internal table to match the numbers with reel locations. The reels then stop at the corresponding positions to reveal the winning combination. If the machine has a progressive jackpot, the jackpot grows with each bet made. Players who bet a maximum amount of coins are known as max-bet players. Although luck plays a large part in slot success, players can increase their enjoyment by choosing machines that suit their personal tastes. In addition, they should know the rules of each game before playing it.