$SPY Why are swing highs / lows even important? Without having liquidity on the chart like I do here, they are showing you where the market is providing liquidity. When liquidity zones break (market participants hitting the bid or ask) this tells you that swing high or low that was previously important to the market makers has been defeated, at least temporarily. This is only demonstrating using a 5 min chart on $BTC.X but you can extrapolate this out to any timeframe. The larger the timeframe, the more important the event.