Mobile apps function by executing code written in programming languages like Java or Swift on mobile devices. They interact with device hardware (like cameras or GPS) and utilize APIs to access data from servers or other sources. App developers in dallas design apps with specific functionalities and user interfaces tailored to enhance user experience. They ensure compatibility across different devices and operating systems through rigorous testing. Once downloaded from app stores, apps run independently, processing user inputs and displaying information or performing actions based on programmed logic, thereby enabling a wide range of tasks from communication to productivity and entertainment.