Mobile app development involves creating software applications for mobile devices such as smartphones and tablets. The app can be developed for either the iOS operating system used by Apple devices, or the Android operating system used by many other brands. To make money through mobile app development, you can either sell your apps on the official app stores such as the Apple App Store or Google Play Store, or through your own website. Developing a successful mobile app requires technical skills in programming languages such as Swift or Java, as well as a good understanding of user experience (UX) design and app architecture. Reference website examples: Apple App Store: https://apps.apple.com/ Google Play Store: https://play.google.com/store Freelance app development websites: Upwork: https://www.upwork.com/ Fiverr: https://www.fiverr.com/