A price level or price zone where traders and investors are willing to sell a security, thereby creating supply at that price level, causing the price to stop rising and start falling.
Resistance is a downward movement in price caused by supply.
Historic price resistance levels or historic price resistance/support zones are key price levels on price charts that tend to act as a catalyst for the anticipated change in the direction of price.
Price resistance zones are a naturally occurring part of the price cycle pattern and frequently a self-fulfilling prophecy.