The rsi full form Relative Strength Index.
R = Relative
S = Strength
I = Index
The Relative Strength Index (RSI) is a technical research metric for financial instruments. J. Welles Wilder created the RSI to quantify the pace and adjustment of price movements. The RSI scale varies from 0 to 100, with 0 being the lowest and 100 being the highest. A value of 30 or less indicates that a security is undervalued, whereas a value of 70 or more indicates that a security is being overvalued. RSI is considered oversold when it falls below 30 and overbought when it rises above 70.
100 – [100/(1+RS)] = RSI
Average Gain / Average Loss = Relative Strength (RS) for the given time. The default time for calculating the RSI is 14.