Hammer

The shape is defined by proportion, not by size. The real body sits in the upper part of the candle's range, the lower wick runs at least twice the length of that body, and the upper wick is short or absent. Colour is not part of the definition, although a body whose close sits above its open is conventionally treated as the firmer version of the same shape.

What the candle records is an interval in which price traded well below the open and returned close to it before the interval ended. Location is as much a part of the name as geometry: the identical candle appearing after an advance is called a hanging man, and nothing but the preceding move separates the two.

The common error is reading one in isolation. A candle summarises a single interval, so the shape recurs constantly inside ranges and inside declines that carry on, and most conventions treat it as unconfirmed until a later candle closes above its high. Practitioners also disagree on how strict the proportions have to be. Some require the body in the top third of the range with no upper wick at all, others accept any candle with a dominant lower wick, and the reliability reported in tested work moves with the definition the test used.