Apps on Your Phone
An APP (short for application) is a piece of software designed to run on a phone or tablet. Each icon you see on your phone screen is an app. Some come pre-installed (Camera, Messages, Phone). Most you DOWNLOAD from an app store (App Store on iPhone, Google Play on Android).
Apps are built by DEVELOPERS. They write CODE that tells the phone what to do — when you tap, what to show, how to save your data, when to use the camera or microphone. Apps can be SIMPLE (a calculator) or HUGELY COMPLEX (a video game with millions of users). All of them follow the same basic pattern: input from the user → process → output on the screen.
When you tap an app icon, what happens?
Apps can DO things web pages can't. Use the camera, GPS, fingerprint scanner, accelerometer (motion). Send notifications. Work offline. Many big companies build BOTH a website AND an app for their service — they reach more users that way.
App Audit
Look at your phone screen (with permission). Pick 3 apps. For each, ask: what does it DO? What sensors does it use (camera? location? mic?)? What would the world be like without it?
Apps changed daily life. Maps, banking, communication, learning — all in your pocket. Knowing how they work is the first step toward maybe one day BUILDING your own.
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