A vertical line that extends upwards or downwards from the body of a candlestick bar and terminates at the highest or lowest price within a given timeframe.
A wick gives an indication of price movement on a candlestick chart. It tells the trader how and in what direction price has moved during the period of trading. It is mainly used to understudy market volatility and direction, helping traders make informed decisions.
The longer the wick, the more volatile the price movement. If the candlestick bar has a short wick or none in either direction, it means that price didn't move much beyond the opening or closing price.