Hammer

A hammer is a candlestick with a small body near the top of its range and a lower wick at least twice the body's height, printed after a decline. The shape shows sellers pushing price sharply lower intraday and buyers reclaiming almost all of it by the close.

Location does most of the work. The same shape printed at a fresh high (there it is called a hanging man) or in the middle of a range carries a different read. A hammer landing on a prior support level, with the next candle closing above the hammer's high, is the standard confirmation sequence.

Hammers mark where dip buyers showed up once. They do not obligate those buyers to show up again, and hammers in strong downtrends get run over regularly.