Book excerpt: Learn to build mobile apps for Android devices with MIT App Inventor, a visual drag-and-drop programming language like Scratch. You've swiped and tapped your way through countless apps, but have you ever created one? Now you can, thanks to Learn to Program with App Inventor. In less than an hour, you'll be able to build and run your first app! App Inventor is a free software for making Android apps. All you need is a PC with an Internet connection to build your app, and a mobile phone for testing. You'll use a simple drag-and-drop interface, which minimizes errors and avoids too much typing. A certified App Inventor Master Trainer, Logan breaks down each project into logical steps, lists the components you'll need, and then shows you how to create screen designs, control program flow with conditionals and loops, and store data in variables and lists. Once you've tested the app on your phone, you can test what you learned with challenges at the end of each chapter. You'll build cool apps like: * Hi, World!: Use your voice to send a text message * Practice Makes Perfect: Rehearse a speech or dance routine with this video recording app * Fruit Loot: Catch randomly failing fruit in this exciting game * Beat the Bus: Track a friend's journey using location services and maps * Virtual Shades: Take a selfie, then try on some virtual sunglasses Join the 6 million people who have tried App Inventor, and make the journey from app user to app inventor.