A special kind of classification rule are binary classifications.

A binary classification is such that the label y can take only a two values.

Thus, classifiers build a chain where each of them learns binary classification of a single label.

Finding a person innocent or guilty can be viewed in mathematical terms as a form of binary classification.

In binary classification, precision is analogous to positive predictive value.

In binary classification, recall is often called sensitivity.

If the test result is of a binary classification into either positive or negative tests, then the following table can be made:

During the 50 years of Japanese colonial rule (1895-1945), anthropologists from Japan maintained the binary classification.

Some classifiers make a binary classification for a test example, while others assign a probability of being a keyphrase.

Hypothesis testing is therefore a binary classification of the hypothesis under study.