Application development is the process of designing, creating, and maintaining software applications for various platforms, such as mobile, web, and desktop. It involves writing code, testing, and deploying apps to meet specific business or user needs. App development includes planning, designing, developing, testing, and maintaining apps, ensuring they are user-friendly, secure, and functional. It involves various programming languages, frameworks, and tools to create apps for Android, iOS, Windows, and other platforms, helping businesses and individuals to automate processes, improve efficiency, and reach their target audience.