RSI stands for Relative Strength Index. It is a momentum indicator used in technical analysis to measure the speed and change of price movements. RSI is often used to identify overbought or oversold conditions in a market, indicating potential trend reversals. The scale ranges from 0 to 100, with readings above 70 considered overbought and readings below 30 considered oversold. Traders use RSI to help assess the strength and direction of a trend and to make informed decisions about buying or selling assets.