An Aspect Oriented Programming (AOP) developer designs and implements software using a programming paradigm that aims to increase modularity by allowing the separation of cross-cutting concerns. They use AOP to encapsulate behaviors affecting multiple classes into reusable modules called aspects. These include logging, error handling, or transaction management. They essentially weave these aspects into the main code at compile time, runtime, or post-compile time, ensuring that the core logic remains uncluttered. By doing this, they enhance code readability and maintainability, promote code reuse, and improve system modularity. They may also use AOP for debugging and performance optimization.