The ZoneTrade Forex Indicator is a popular and free MT4 indicator used by many Forex traders. The indicator works by plotting a series of colored lines on the chart that indicate the current trend of the market. The lines are color coded to indicate whether the market is in an uptrend, a downtrend, or in a range. It also provides a visual representation of support and resistance levels, which can be used to identify potential trading opportunities. The indicator is easy to use and understand, making it a popular choice among Forex traders.