Aspect-Oriented Programming (AOP) is a programming paradigm that improves modularity by separating cross-cutting concerns, such as logging, security, and error handling, from the main code. Instead of scattering these concerns across multiple modules, AOP encapsulates them into aspects, which can be applied across various parts of an application. This approach reduces code duplication, enhances maintainability, and keeps the core business logic clean. AOP is often used alongside object-oriented programming and is supported by frameworks like Spring AOP (Java) and PostSharp (.NET), allowing developers to manage complex software systems more efficiently.