A slot is a dynamic placeholder that either waits for content to be added (a passive slot) or calls out for content through a scenario or targeter (an active slot). Renderers specify the visual output of slots.

The word “slot” comes from the Dutch sleutel, from Proto-Germanic *slutila (“bolt, bar, lock”), perhaps from PIE root *klau-(“hook, nail, pin”). A narrow opening into which something else may be fitted. Hence, the senses of “narrow opening in which something might be inserted” and “position in a machine, timetable, or other sequence”; also, the center spot at a newspaper copy desk (as opposed to the rim of the circular or semi-circular space occupied by the chief subeditor). The figurative sense of “time allotment or period” is attested from 1940.

Using time slots to establish important deadlines can be helpful for managing multiple tasks or workflows, particularly in areas where people may need to track and manage many different objectives simultaneously. In business, for example, time slots can help professionals and teams manage information flow to ensure that urgent objectives are given the attention they need to support successful outcomes.

One of the most common misconceptions about slot machines is that a particular machine has a “loose” pay table. This is nonsense because microprocessors inside the machine assign a different probability to each symbol, and a combination that appears on the screen does not mean the odds are in your favor. A simple test is to put in a few dollars and see how long it takes for you to break even. If it is more than a few minutes, the machine probably does not have a loose pay table and you should move on to another machine.