Appium is an open-source tool for automating native, mobile web, and hybrid applications on iOS and Android platforms. How Mobile web apps are accessed using a mobile browser (Appium supports Safari on iOS and Chrome or the built-in â€˜Browserâ€™ app on Android). How the Hybrid apps have a wrapper around a â€œwebviewâ€ â€“ a native control that enables interaction with web content. Projects like Phonegap, make it easy to build apps using web technologies that are then bundled into a native wrapper, creating a hybrid app. Usage of Appium as â€œcross-platformâ€: How quickly you can write tests against multiple platforms (iOS, Android, Windows), using the same API.