Test scripts are detailed instructions used in software testing to verify that a program functions as intended. They outline the steps to be executed, the input data required, and the expected outcomes. Test scripts help ensure consistency in testing and can be reused for future tests, making them an essential part of the software development process. These scripts can be manual or automated. Manual test scripts require a tester to follow the steps and record results, while automated test scripts are executed by testing tools or frameworks. Both types are crucial for identifying bugs and ensuring the quality of software products before release.