There are several main areas of application development, including:

1. Web Development: This area of application development focuses on creating and maintaining websites and web applications. This can include everything from simple static sites to complex dynamic web applications. Web developers use a variety of programming languages, frameworks, and tools to build and test web applications.
2. Mobile Development: This area of application development focuses on creating apps for mobile devices such as smartphones and tablets. Mobile developers use a variety of programming languages and frameworks to create apps for different platforms, such as iOS and Android.
3. Desktop Development: This area of application development focuses on creating software that runs on desktop computers. Desktop developers use a variety of programming languages and frameworks to create applications for Windows, Mac, and Linux.
4. Game Development: This area of application development focuses on creating video games. Game developers use a variety of programming languages and game engines to create games for different platforms, such as consoles, PCs, and mobile devices.
5. Artificial Intelligence/Machine Learning: This area of application development focuses on creating intelligent software systems, for example chatbots, speech recognition software, image recognition, and self-driving cars.
6. Virtual Reality/Augmented Reality: This area of application development focuses on creating immersive and interactive experiences through VR and AR technologies.
7. Internet of Things(IoT): This area of application development focuses on creating software that can interact with and control connected devices and sensors through the internet.

Each of these areas of application development has its own unique set of challenges and opportunities. For example, web development tends to be more focused on creating web-based interfaces and user experiences, while mobile development tends to focus on the performance and functionality of apps on mobile devices. Game development is heavily focused on graphics and performance, while IoT is focused on creating software that can interact with and control physical devices.