Appium is a mobile test automation framework (and tool) for native, hybrid and mobile-web apps for iOS and Android. It uses JSONWireProtocol internally to interact with iOS and Android apps using Selenium’s WebDriver.
It supports Android via uiautomator (API level 16 or higher) and Seledroid (API level lower than 16), iOS via UI Automation, and mobile web as Selenium driver for Android and iOS.
Also if you are familiar with Selenium, then it’s easy for you to use Appium in mobile app testing. They use the same WebDriver and DesiredCapabilities is used in the same way.
Configuring an application to run on Appium has a lot of similarities to Selenium.