Modularity refers to the concept of designing complex systems in a way that allows for easy separation and interchangeability of components. It involves breaking down a system into smaller, more manageable modules that can be developed, tested, and maintained independently. This approach promotes flexibility, scalability, and reusability in system design, making it easier to modify or extend a system without affecting its overall structure. Modularity is commonly used in various fields, such as software engineering, architecture, and manufacturing, to improve efficiency and streamline development processes.