App Inventor 2 is a free, cloud-based development platform that is provided by The MIT Center for Mobile Learning. It is cloud-based service that you can access using a modern web browser. You need to login with your Google account for example your Gmail account to start using the service and build mobile applications.
App Inventor is easy to use, and it has a visual GUI designer with a drag-and-drop code editor. We can test the application on real Android device or on-screen Android Emulator.
App Inventor allows us to easily create apps for Android smartphones and tablets. App Inventor team is also working on a new iOS version, but as of now we can only use for Android OS.
You can explore more about App Inventor at: http://appinventor.mit.edu/explore/
To see and test your app on your phone:
Follow the instructions to connect your phone to App Inventor on your computer.Connect to real device on WiFi using MIT App Inventor companion app on your mobile.
In case, you don’t have Android device, you can test the app using the on-screen Emulator.
App Inventor provides a special editor known as the Blocks Editor to create the actions that the app performs. With the Blocks Editor, you assemble code blocks to create the app’s actions. It’s that simple!