Front-end Development: This is the part of the app that users interact with directly. It includes the app's design elements, navigation, and overall user interface.

Back-end Development: This involves the server-side of the app, where data is stored, processed, and retrieved. It includes databases, APIs, and cloud integration.

Programming Languages: Depending on the platform, developers use different programming languages like Swift (iOS), Kotlin or Java (Android), or JavaScript (cross-platform frameworks like React Native).