Indicators summarize price into a number. Price action reads the candles themselves: their shape, the swings they make, the gaps and blocks a fast move leaves behind. These nodes turn those readings into values and conditions a strategy can use, so an idea like "a hammer at the last swing low" or "the return to a bullish gap" becomes something you can backtest instead of something you eyeball.
They fall into three groups. The candle nodes measure a single bar or match a pattern across a few. The structure nodes track swings, trends and the zones a move leaves behind, and remember them over time. The channel nodes fit a regression line through recent prices and draw a channel around it.
One thing worth knowing before you build. The structure nodes (Swing Points, Market Structure, Fair Value Gap, Order Block) and Multi-Bar Formation carry their own memory through history, so the nodes that need a value's full history behind them, the Crossover, Since, Capture and the State Machine, can't read them. Compare their levels with a Comparison instead, which is exact on every bar.