JUnit is a popular testing framework for the Java programming language. It allows developers to write and run repeatable tests to ensure their code works as expected. By using JUnit, programmers can create test cases that check individual parts of their applications, making it easier to identify and fix bugs early in the development process. One of the key features of JUnit is its simplicity and ease of use. Developers can annotate their test methods with special tags, making it clear which tests are being run. This helps maintain code quality and encourages best practices in software development, ultimately leading to more reliable applications.