A Breaker Block forms when price breaks through an order block that was expected to hold, rendering the original OB "broken." Once this occurs, the zone flips polarity: a bullish OB that failed becomes a bearish breaker block (resistance), and a bearish OB that failed becomes a bullish breaker block (support).
The concept is rooted in the idea that institutional orders that were placed in the original OB have now been hit and reversed. The smart money that accumulated longs in a bullish OB, which then failed, now has an interest in distributing at that same price zone when it is revisited. This is what gives breaker blocks their predictive power.
Breaker blocks are often found at key swing highs and lows after a market structure shift. They are most effective when combined with a Fair Value Gap formed during the break through the original OB and a liquidity sweep above or below the breaker zone.
Tracking breaker block setups in your journal requires recording the original OB timeframe, the reason the OB failed (was there a liquidity sweep?), and whether there was a FVG in the break. Compare your win rate on breakers vs. standard OBs to see which setup has more edge in your trading.