A breakout is a technical analysis term describing when a stock rises through and above a price resistance level and continues to uptrend higher. Resistance is a price level that sellers sell into, causing the stock to deflect back down.
Resistance levels are a price ceiling with too much supply as demand thins out, causing the stock to fall back to a support level. A support level is a price point where buyers are ready and willing to buy. It's a price level where demand is steady enough to absorb the selling. These are absorbing levels where resistance absorbs buyers and deflects them down, and support absorbs sellers to deflect them up.
Breakouts tend to attract more buyers as shares continue to rise. A stock can trade in a defined obvious range for a duration of time, but when it starts to rise through the top of that range on elevated volume, it can form a breakout. An uptrend follows a breakout that raises the stock price by making higher highs on bounces and higher lows on pullbacks.