A COM/DCOM/ATL developer specializes in creating and managing software applications using Component Object Model (COM), Distributed Component Object Model (DCOM), and Active Template Library (ATL). They develop reusable software components that can be incorporated in different applications, enabling efficient communication between various software objects. They also handle the distribution of these components across a network through DCOM, allowing objects to communicate across different computers. Using ATL, they create lightweight COM objects, improving the performance of the system. Their tasks also involve debugging, testing, and maintaining the software to ensure its optimal performance.