The gambler's fallacy is a common misconception about random events. It's the belief that a random event that has happened more (or less) often in the past is more (or less) likely to happen in the future. For example, a gambler might think that if a coin has come up heads 10 times in a row, it's more likely to come up tails on the next flip. But that's not the case - the odds are always 50/50 for each individual flip, regardless of the past results. This fallacy can be dangerous because it can lead people to make bad decisions, like betting too much money on something