Web services are software systems designed to support interoperable machine-to-machine interaction over a network services to run on a variety of software platforms and hardware architectures. This interoperability is gained through a set of XML-based open standards, such as WSDL, SOAP, and UDDI. These standards provide a common approach for defining, publishing, and using web services.

Interoperability is the most important principle of SOA which can be realized through the use of web services. The advent of web services and SOA offers potential for lower integration costs and greater flexibility.