Pin bar / Hammer
A candle with a long wick one side, small body at the opposite end. Reversal signal when it fails a level.
Long lower wick (hammer) at the bottom of a pullback = buyers stepped in. Long upper wick at the top = sellers. Quality matters: wick should be 2-3x the body, closing near the body's far end. Often the shape of a valid rejection candle.
Related
Learn to actually use Pin bar / Hammer.
Definitions are the easy part. The free first five modules put this on a real chart and make you do the work. No card required.