A search for "slots free spins demo" is usually about how a slot hands out its wins from one spin to the next. Two slots can list the same return and still feel like different games, because the return says nothing about how the money arrives. Volatility and hit frequency describe that part: how often a spin pays anything, how large the rare wins are and how long the dry spells last. Together they decide what a fixed budget is likely to buy in playing time.
A session budget is easier to judge when it is counted in spins. Dividing the money set aside by the stake gives the number of spins it covers before any wins, and on a volatile game a long run without a meaningful payout is a normal event within that count. Lowering the stake stretches the same budget across more spins and gives the rare features more chances to appear. Raising it shortens the session without improving the odds of any one spin.
Volatility measures how widely results scatter around the average return. A game rated low pays modest amounts at a steady pace, and a game rated high concentrates its return in rare, large wins, often inside a bonus feature. Studios describe it on scales of three or five levels, sometimes with lightning bolts or bars instead of numbers, and the scales are not comparable between studios. Choosing a level is a matter of taste and budget, while the cost over the long run does not move.
Measured returns drift away from the theoretical figure over any stretch a person can play, and the gap narrows only across millions of spins. Tracking sites that pool results from many players show this clearly: a game can run far above or below its figure for weeks. Demo modes normally use the same maths as real play, so a free session shows the rhythm of a game, although a short demo run says as little about the true return as a short session for money.
Games that sell entry to their bonus list a separate return for the bought feature, sometimes higher and sometimes lower than the base game, in the rules.
Many slots limit the largest win a single spin can produce, often as a multiple of the stake; once reached, the round ends and further winnings are forfeited.
Lowering the stake stretches a budget across more spins and gives rare features more chances to appear, while raising it shortens the session without improving the odds.
Studios describe it on scales of three or five levels, sometimes as lightning bolts or bars, and those scales cannot be compared between different studios.