Appium is a tool based upon Webdriver API and its JSON Wire Protocol, that is used for app driving on mobile devices and is getting more and more popular in mobile test automation.

This tool has a lot of advantages:

• clean and simple API on many programming  languages
• wide platform support: IOS, Android, FirefoxOS
  
• wide app type support: native, web, hybrid
  
• easy integration with other tools

Moreover, appium is popular among various vendors like infrastructure-providing cloud services.

Let's discuss how you would execute your appium tests in clouds on real devices and emulators, what should be configured in order to do that using Sauce Labs, Browser Stack и AppThwack as an example.