You can build many different types of apps with App Inventor. Often people begin by building games like MoleMash or games that let you draw funny pictures on your friend’s faces. You can even make use of the phone’s sensors to move a ball through a maze based on tilting the phone.

But app building is not limited to simple games. You can also build apps that inform and educate. You can create a quiz app to help you and your classmates study for a test. With Android’s text-to-speech capabilities, you can even have the phone ask the questions aloud.

To use App Inventor, you do not need to be a developer. This is because instead of writing code, you visually design the way the app looks and use blocks to specify the app’s behavior.

The App Inventor team has created blocks for just about everything you can do with an Android phone, as well as blocks for doing “programming-like” stuff– blocks to store information, blocks for repeating actions, and blocks to perform actions under certain conditions. There are even blocks to talk to services like Twitter.

App Inventor is simple to use, but also very powerful. Apps you build can even store data created by users in a database, so you can create a make-a-quiz app in which the teachers can save questions in a quiz for their students to answer.

Reference:
Google App Inventor. From Wikipedia, the free encyclopedia.
App Inventor for Android.