A narrow notch or groove, as in a keyway in machinery or a slot for a coin in a vending machine. Also a position in a group, series, or sequence.
A number of different variations of the payline are available in online slots. Most of them are called cluster pays and work in a slightly different way from traditional paylines. Usually they pay out when symbols form in a cluster of 3 or 5 on the reels, rather than needing to line up in a row as in traditional slots. They tend to offer higher payouts, but can have a higher risk factor as well.
Another common variation is the all ways to win type of payline. This pays out when a matching symbol appears on every reel (left to right) and is triggered in a winning location. This can be found on many games, although it is worth checking the pay table to make sure you know what to expect.
It is important to understand how paylines work in a slot machine before you play. It is also useful to look at the paytable, which will give you information about how much each spin costs and which symbols are associated with which prize values. It is important to remember that, even if you have hit a winning combination, it may not necessarily be worth the prize amount indicated on the paytable. This is because slot machines have weighted probabilities for each symbol, which can result in symbols appearing close together on a reel but actually having very different odds of hitting.