A test plan is a comprehensive document that outlines the approach, objectives, and procedures for testing a product or system. It serves as a roadmap for the testing process, detailing the scope, resources, and timelines required to ensure the quality and functionality of the product. A well-crafted test plan includes a detailed description of the testing environment, test cases, and expected results, as well as any risks and contingencies. It is an essential tool for software development teams to ensure that their product meets the desired standards and specifications before it is released to the market.