Here is the definition of Sortino Ratio.
https://www.investopedia.com/terms/s/sortinoratio.asp
The Sortino ratio is a variation of the Sharpe ratio that differentiates harmful volatility from total overall volatility by using the asset's standard deviation of negative portfolio returns, called downside deviation, instead of the total standard deviation of portfolio returns.
Description changed:
Here is the definition of Sortino Ratio.
https://www.investopedia.com/terms/s/sortinoratio.asp
The Sortino ratio is a variation of the Sharpe ratio that differentiates harmful volatility from total overall volatility by using the asset's standard deviation of negative portfolio returns, called downside deviation, instead of the total standard deviation of portfolio returns.