Selenium with Python is an open-source test suite that facilitates cross-platform browser automation, popular for its ease of use and support for multiple programming languages. This tutorial focuses on using Selenium with Python through the PyUnit framework, a unit testing framework derived from JUnit, which is officially included in Python from version 2.5 as unittest. The tutorial explains the building blocks of Selenium with Python's unit test framework, including Test Loader, Test Runner, Test Suite, Test Case, and Test Report, alongside the use of setUp() and tearDown() methods for initialization and cleanup. It provides an overview of important classes in the unittest package such as TestCase, TestSuite, and TestResult, detailing the use of assertions to validate test outcomes. The tutorial includes sample code to demonstrate the PyUnit/unittest framework in practice and discusses how it can be employed for module-level and cross-browser testing. Additionally, it highlights the flexibility of using PyUnit for writing tests in other languages like Java through the Jython framework.