The "key zone" for Bitcoin refers to critical price levels that act as support or resistance, influencing its price movement. These zones are determined by historical price action, where Bitcoin has previously reversed or consolidated. Key zones often include psychological levels (e.g., $20,000, $50,000), Fibonacci retracement levels, and moving averages like the 50-day or 200-day. Traders focus on these areas for potential breakouts or pullbacks. A strong support zone indicates buying interest, while resistance zones suggest selling pressure. Monitoring these zones helps traders anticipate potential price action and make informed decisions on buying or selling.