What is the purpose of using JUnit annotations in test classes?

JUnit annotations in test classes serve the purpose of providing metadata to the JUnit framework about how to run the tests. Annotations help in defining the behavior of test methods and classes, such as identifying methods as test cases, setting up test fixtures, executing methods before or after tests, and handling exceptions. Annotations make it easier to write and maintain test cases by providing a clear structure and allowing for better organization of test logic.