A computer program developer designs, writes, tests, and maintains software or applications to meet specific needs. They start by identifying the need, then plan and create a design to solve that problem. They write code in various languages, depending on the platform and software requirements. After the program is developed, they test it to ensure it functions correctly and debug any errors. They also make updates or enhancements to improve the software's performance. They often collaborate with other developers, systems engineers, and clients to ensure the software meets the intended needs and provides a user-friendly experience.