The Up Down Indicator is a popular and free Forex indicator for MetaTrader 4 (MT4) that provides traders with an easy-to-read visual representation of the direction of the market. The indicator utilizes a simple but effective algorithm to determine whether the market is trending up or down. It displays a green arrow for an uptrend and a red arrow for a downtrend. It is simple to use and can help traders identify the direction of the market quickly and accurately.