A breakout in trading refers to a situation where the price of a stock or asset moves decisively above a resistance level or below a support level with increased volume, signaling the start of a potential new trend. It indicates that the previous price range or consolidation phase has ended, and buyers (in an upside breakout) or sellers (in a downside breakout) have gained strong control. Traders often see breakouts as opportunities to enter trades early in a trend, but confirmation through volume and follow-through is important to avoid false breakouts.