A narrow notch, groove or opening, such as a keyway in a lock or the slit for coins in a machine. Also: A position or time in a schedule, program, or activity. The slot in the wing of an airplane, for example, provides an air gap to reduce drag. To place or fit something into a slot: The book slotted into the shelf easily.

A slot is a container for dynamic content on a Web page. A slot can be passive (waiting for content to call it) or active (calling a renderer to fill the slot). Slots work with scenarios to manage content on the page and are the basis of many of the Web page layouts we use today.

Invented in the late 1800s, slots were once found in saloons and dance halls. Originally, they had three spinning reels with symbols that lined up to make poker hands when a lever was pulled. Charles Fey’s machine allowed automatic payouts and replaced the poker symbols with diamonds, hearts, horseshoes, and liberty bells (hence the name). Later, slots were developed with additional paylines and bonus features, including Wilds that act as substitutes for other symbols and can open up special game levels and jackpots.

While some people believe that following superstitions can improve their chances of winning, the truth is that random number generator software determines the outcome of each spin. Throwing more money at a slot just because it “might be the one” is a sure way to lose money.