Pytest is an open-source testing framework for python that is widely used for its simplicity and flexibility in writing and executing test cases. It allows developers to write simple as well as complex tests using a minimal amount of code. Pytest supports various types of tests, including unit tests, functional tests, and integration tests. One of its key features is the use of fixtures, which are functions that provide a fixed baseline for tests, allowing for setup and teardown processes to be defined in a reusable manner. Additionally, Pytest supports powerful assertions, detailed output for test failures, and extensive plugin architecture that extends its functionality with features like test coverage, parallel test execution, and integration with other tools. By promoting best practices in testing and providing clear, concise syntax, Pytest helps developers maintain code quality and improve software reliability.