Doji

Formation
These candle lines have no real body. Market opens and closes at the same level. Only wicks are present above and below a small horizontal line.

Importance
This happens when both supply and demand are almost equal. That means the market is neutral or it is deciding the next movement. They may occur at many places in a chart. But at the top and bottom of a trend they become significant. Because of this they form important support and resistances.

The market can open and close at the low of the day. The resultant formation is a Gravestone Doji. If the open and close are at the high of the day we get a Dragon Fly Doji.