Probability ITM (“In the Money”) is the chance that the underlying asset’s price will end up either above a call’s strike price or below a put’s strike price at the options’ expiration.
The Probability ITM is a profitability indicator that looks at the probability of your options setup will expire in the money.
If you are using a net-long options setup, then you will want to maximize this criterion.
If you are using a net-short options setup, then you will want to minimize this criterion. Alternatively, you can use Probability OTM and maximize that criterion instead.