Horizontal support / resistance lines are formed when a stock touches and bounces at, or very near, the same price level. As with drawing any trendlines and support/resistance lines, it is not a perfect science. If it’s close, it counts. Look for volume spikes on the candles where it hits support or resistance for extra verification. And understand that at some point support/resistance will fail to hold and the stock will move through it. It may eventually come back to retest the support/resistance level, and this becomes another great place to enter a trade.