Relative Strength Index (RSI) is a valuable technical indicator which gives insights to make informed decisions. It tells about stock's momentum and potential price movements. RSI measures the speed and change of price movements on a scale from 0 to 100, and readings above 70 indicate an overbought condition, while readings below 30 suggest an oversold condition. Analysing RSI trends can help investors gauge a stock's potential for price reversals or continued momentum.