How to read it
A doji does not say which way price will go.
It shows that, within that period, price moved but ended near where it started.
Traders often read it as a pause or indecision.
It carries more meaning after a long move than in the middle of a directionless market, and traders usually wait for the next candle before drawing any conclusion.
Note: These are descriptions of chart-reading conventions. A flat body measures the relationship of open and close. It cannot establish market participants’ intentions or verify how often traders wait. A doji can also have no wick if all four prices are the same.
Common types (by the shadows)
Long-legged doji: Long shadows on both sides.
Dragonfly doji: Long lower shadow, almost no upper shadow.
Gravestone doji: Long upper shadow, almost no lower shadow.
What it is not
It is not a signal on its own.
After a doji, price can reverse or continue; both happen.