# What is a discrimination threshold of binary classifier?

With respect to ROC can anyone please tell me what the phrase "discrimination threshold of binary classifier system" means? I know what a binary classifier is.

Classifiers often return probabilities of belonging to a class. For example in logistic regression the predicted values are the predicted probability of belonging to the non-reference class or $\text{Pr}(Y = 1)$. The discrimination threshold is just the cutoff imposed on the predicted probabilities for assigning observations to each class.