A bar shows a vertical line representing the high to low trading range for the bar. Tick marks on the left and right side of the vertical bar mark the open and closing price of the bar. Daily, weekly, and monthly bars are color coded with an up color or down color based on whether the closing price of the bar is higher or lower than the closing price of the prior bar.
The default colors used are specified in Chart General Preferences. Intra-day minute bars may be color coded based on either the closing price of the previous bar or on the opening price of the bar. When viewing a tick by tick chart, if bar format is chosen, the trading range of the bar is drawn to depict the bid-ask range (instead of high low range). The trading price of each tick is then depicted as a mark through the trading range. The is a convenient way to watch how an instrument is trading relative to its current bid/ask.