Appium is an open-source testing framework that allows users to test iOS and Android mobile applications, including browser-based UI components, native user components, or hybrid combinations thereof. It uses the Selenium driver technology and can be used with various programming languages such as Java, C#, PHP, Ruby, Python, or JavaScript. Appium provides a service through the Appium Server, which allows users to write tests in their preferred language and execute them against a local instance of the server or an external server location, such as SauceLabs. The Appium Desktop tool is used to fire up mobile applications in emulators, identify elements, and perform actions on them. By using Appium with a continuous integration process, developers can automate testing for their mobile applications, reducing the burden required to make quality software, especially when combined with an Appium service like SauceLabs.