Once you have defined your test scope, you need to choose the methods that you will use to test your app or website on different devices, platforms, and browsers. There are three main methods that you can use: real devices, emulators, and cloud-based testing tools. Real devices are the most accurate and reliable way to test your app or website, as they reflect the actual user experience and environment. However, they are also costly, time-consuming, and difficult to maintain and update. Emulators are software programs that simulate the behavior and features of a device, platform, or browser on your computer. They are cheaper, faster, and easier to use than real devices, but they may not be able to replicate some aspects of the device, such as touch screen, camera, or sensors. Cloud-based testing tools are online services that provide access to a large pool of real devices, platforms, and browsers that you can test your app or website on remotely. They are convenient, scalable, and cost-effective, but they may have some limitations in terms of security, network connectivity, and customization.