App development services refer to the process of designing, creating, and maintaining mobile and web applications. These services may include the development of custom software, integration with existing systems, and ongoing maintenance and updates. App development companies often specialize in a specific platform, such as iOS or Android, or a specific technology, such as React Native or Xamarin. Additionally, they may provide a range of services, including app design, user experience (UX) research, and quality assurance (QA) testing.