Exact formation
Opening and closing practically the same next to the maximum, with a long lower shadow and almost no upper shadow.
What is happening in the market
The selling drove the price much lower, but demand brought it back to the opening point.
Where it matters
It can be bullish after a fall and on support; without that location it only describes inferior rejection.
How to confirm it
Subsequent close above the doji high.
When it is invalidated
Breaking the shadow minimum.
Common mistake
Confuse it with a normal doji that has long shadows on both sides.