Learn to play slots better
Not all slot machines are created equal.
Each one, in addition to having different symbols, perhaps even new computerized layouts complete with bonus rounds, also may reward the customer with different payouts, depending on where those spinning wheels ultimately end up.
Normally, each machine will have a "pay table" listed, where it is spelled exactly what symbols must appear, and in what order, so that the customer wins and hears the "clink, clink" of coins landing in the payoff bin. The "payline" is where these symbols must land in order to count.
Many machines, especially the older ones, may allow the customer to see several rows of symbols one the slots comes to a rest. Some newer gamblers might get confused and think they have won when a winning combination is right there in front of their eyes, if they don't realize the sequence they are looking at is not the indicated "payline." Only the payline counts.
Many newer machine offer you a chance to put in a few extra coins to add additional "paylines" to the mix. However, keep in mind that while this may seem like a good deal, psychologically, it really isn't. Most computerized machines are not really "spinning" - but rather settling on a pre-determined payout scheme based on a mathematically probability of payout. This means that you have either won or lost, depending on the random outcome generated at the moment of the "pull" and regardless of how many "paylines" are visible, your fate has already been determined.