Middleware is software that acts as a bridge between different applications or services, allowing them to communicate and share data. It simplifies the development process by providing common services and functions, enabling developers to focus on building their specific applications without worrying about the underlying complexities of communication. Middleware can be found in various forms, such as message brokers, database middleware, and web servers. It plays a crucial role in modern software architecture, especially in distributed systems, where multiple applications need to work together seamlessly across different platforms and environments.