Oracle Fusion Middleware is a collection of standards-based software products that spans a range of tools and services: from Java EE and developer tools, to integration services, identity management, business intelligence, and collaboration. Oracle Fusion Middleware offers complete support for development, deployment, and management.
Specifically, middleware is the software that connects software components or enterprise applications. Middleware is the software layer that lies between the operating system and the applications on each side of a distributed computer network.
Typically, middleware supports complex, distributed business software applications.
Middleware is also the infrastructure which facilitates creation of business applications, and provides core services like concurrency, transactions, threading, messaging, and the SCA framework for service-oriented architecture (SOA) applications. It also provides security and enables high availability functionality to your enterprise.
Middleware includes Web servers, application servers, content management systems, and similar tools that support application development and delivery.