Mobile app development is the process of creating software applications that run on mobile devices, such as smartphones and tablets. This involves designing, coding, and testing apps to ensure they function properly on various operating systems, like iOS and Android. Developers use programming languages like Swift for iOS and Java or Kotlin for Android to build these applications. The development process typically includes several stages, such as planning, designing the user interface, writing code, and conducting quality assurance tests. Once completed, apps can be distributed through platforms like the Apple App Store or Google Play Store, making them accessible to users worldwide.