A slot is a narrow opening or groove, especially one in the side of something. You can put letters and postcards into mail slots in post offices, or you can use a slot on your computer to save files. The term is also used to refer to a position on an NFL team, where a receiver lines up just inside the line of scrimmage. Some teams have more slots than others, and the best slot receivers can get much more playing time than other wideouts.
In a slot machine, you insert cash or, in “ticket-in, ticket-out” machines, a paper ticket with a barcode, and then activate the reels by pressing a lever or button (either physical or virtual). The symbols on the spinning reels then appear to rearrange themselves, sometimes creating winning combinations of symbols on paylines that run horizontally, vertically, diagonally, or in other patterns. When a winning combination appears, you receive credits according to the pay table. Most slot games follow a theme, such as characters from Ancient Egypt or Greece or card numbers from nine thru ace, and they may include special symbols, such as wilds that substitute for other symbols to complete winning lines.
Some slot games have multiple paylines, and you can often determine the number of active paylines by looking at the display on the machine. The pay table shows how many credits you can win if specific symbols line up on the payline, and some machines allow you to select which lines to play.