Support and Resistance

Support is a price level a stock or index has bounced off of more than once, as if there's a floor there; resistance is the mirror image, a price level it's struggled to break above, as if there's a ceiling. Neither is a law of physics, they're just prices where enough buyers or sellers have historically shown up to change the trend, often because round numbers or past highs and lows sit psychologically in traders' minds. When a price finally breaks through one of these levels, especially on high volume, it's often treated as a meaningful signal that the trend has genuinely shifted.