In trading, support refers to a price level at which demand for a stock or other security is thought to be strong enough to prevent the price from falling further. Support levels are often determined by analyzing past price movements and identifying areas where buyers have consistently stepped in to buy the security and prevent a further decline in price. Support levels can act as a floor for a stock's price, and if the stock's price falls to a support level and then starts to rise, this is seen as a bullish sign. On the other hand, if the stock's price falls through a support level, this can be seen as a bearish signal and an indication that the trend may be shifting from bullish to bearish. Traders and investors use support levels as a key factor in determining entry and exit points for trades, and as a way to set stop-loss orders.