A Service Registry is a centralized database that keeps track of services available in a network. It allows different applications or microservices to discover and communicate with each other efficiently. By registering their details, services can be easily located, which simplifies the process of integration and enhances system reliability. In a microservices architecture, the Service Registry plays a crucial role in managing service instances. When a service starts, it registers itself with the registry, and when it goes down, it deregisters. This dynamic management helps maintain up-to-date information about available services, improving overall system performance and scalability.