Sometimes (most often in Forex trading) bullish candles are white or transparent, while bearish candles are black or grey. Many charting tools and platforms, including the CScalp trading terminal, allow you to customize candles and set your own colors.
A candle is a time unit of price development over time. On a 5-minute time frame, each candle represents 5 minutes of price movement. On an hourly TF, each candle is 1 hour, and so on.
In a bullish candle, the lower shadow shows the lowest price over the time period, while the upper one is the maximum value. The lower end of the body is the opening price of the candle, and the upper end is its closing price.
A bearish candle is an exact opposite. The wick also show the minimum and the maximum price. The difference is that the upper side of its body is the opening price, while the lower one is its closing.
That said, it should be noted that the type of candle is only known after it’s closed. It’s not uncommon for candles to shift between bullish and bearish many times while they’re open. This is especially relevant to smaller time frames (1m, 5m, and 15m). On larger time frames though (4H and upwards), it’s usually more clear where the price is headed, and each candle’s type is known well before it’s closed. The length of the candle depends on the amplitude of the price moves. The greater the spread between prices, the longer the body will be. Long candles translate to high volatility, a feature much sought after by scalpers and day traders.
Most often, the word “shadows” is applied to both the lower and the upper line of the candle. Some sources use “shadow" only for the bottom line, and "wick" only for the top line.