Decision trees classifiers can be used to classify data points, such as in the following examples:

• Mortgage applications: To train a binary classifier to determine whether an applicant is likely to default. 
• Customer segmentation: To categorize customers into high-worth, medium-worth, and low-worth customers so that marketing strategies can be customized for each category.
• Medical diagnosis: To train a classifier that can categorize a benign or malignant growth.
• Treatment-effectiveness analysis: To train a classifier that can flag patients that have reacted positively to a particular treatment.