The long white line is a sign that buyers are firmly in control - a bullish candlestick.
A long black line shows that sellers are in control - definitely bearish.
Marubozu are even stronger bull or bear signals than long lines as they show that buyers/sellers have remained in control from the open to the close -- there are no intra-day retracements.
It is a type of candlestick charting formation that appears when a security's price does not trade outside the range of the opening and closing prices.
Investopedia Says: This type of candle suggests strongly that there is a greater demand for the stock than there is willingness for people to sell it. The opposite is true when the marubozo appears on a down day (when the opening price is equal to the high of the day).