What is Specificity in Machine Learning?

Specificity

Specificity is the fraction of values predicted to be of a negative class out of all the values that truly belong to the negative class (including false positives). This measure is similar to recall, but describes the offset in correcting predicting negative values. It is also called the true negative rate.
specificity = predicted true negatives / (true negatives + false positives)

Example

There are 100 credit card transactions; 90 transactions are legitimate and 10 transactions are fraudulent (negative class). If your model predicts that 20 transactions are fraudulent, its recall is:
50% = 10 true negatives / (10 true negatives + 10 false positives)