Candlestick

A chart mark that carries four values for one interval: the price at which the interval opened, the highest and lowest prices traded within it, and the price at which it closed. The rectangular body spans the open and the close. The lines above and below it, called wicks or shadows, reach to the high and the low. The body is filled or coloured one way when the close sits above the open and the other way when it sits below, so direction is legible without reading a single number.

The interval is set by the chart's time frame, not by the market, which is why the same trading session produces a dense sequence of small candles on a five minute chart and a single candle on a daily one. Nothing is lost or added by that choice, but the shapes change completely, and a formation that looks decisive on one frame frequently does not exist on the frame above it.

The usual trip is reading the body as the range. It is not. The range is the distance from wick to wick, and the body only reports where the interval started and ended. A candle also says nothing about the path taken inside it: a period that fell hard and recovered, and a period that drifted quietly upward, can close as the same mark. Practitioners disagree sharply about how much a single candle signals, and most who use them treat one candle as a description of the interval rather than as evidence on its own.