What is RSI?

The Relative Strength Index (RSI) is a momentum oscillator that measures the speed and magnitude of recent price changes on a scale of 0 to 100. Readings above 70 are traditionally considered overbought and below 30 oversold. RSI is best used with trend context rather than in isolation — in a strong uptrend, RSI can remain elevated for extended periods. Divergence between price and RSI can hint at weakening momentum.