The Doji Candlestick patter looks like a vertical line crossed with a smaller horizontal line. The vetical line is the price movement throughout the time period that this candlestick represents. And the horizontal line indicates that the Real Body of the candlestick is non existent, because the opening and closing price are the same. Although the opening and closing price do not have to be exactly the same, so the Real Body can be slightly visible, for the candlestick to be called a Doji.
This candlestick pattern shows you that neither bulls nor bears could gain control and represents a standoff in the price of the period the candlestick represents.
If the opening and closing price are exactly the same the Doji is considered to be a stronger signal then when there is a very thin body. Although a small body amongh other small bodies is not considered to be a robust signal, a thin body among long bodies is.