A person playing a slot machine purchases the right to play by inserting coins, cash, or in newer machines, a bar-coded paper ticket (known as "ticket in/ticket out" machines), into a designated slot on the machine. The machine is then activated by means of a lever or button, or on newer machines, by pressing a touchscreen on its face.

The game itself may or may not involve skill on the player's part — or it may create the illusion of involving skill without actually being anything else than a game of chance.

There are many different kinds of gambling slot machines in places such as Las Vegas. Some of the most popular are the video poker machines, in which players hope to obtain a set of symbols corresponding to a winning poker hand. Depending on the machine, players can play one, 100, or more hands at one time.

Becoming more popular now are the multi-line slots. These slots have more than one payline. Reel slots commonly have three or five paylines, while video slots have 9, 15, 25, or even 100 different paylines.

Video slots are themed slots, with graphics and music based on popular entertainers or TV programs with a bonus round. Most accept variable amounts of credit to play with 1 to 5 credits per line being typical.

The higher the amount bet, the higher the payout will be. Of course, there are the standard 3 - 5 reel slot machines, of various types. These are the typical "one-armed bandits".