SOAP vs REST API

• SOAP API. SOAP has been the standard web service protocol for over a decade. SOAP messages are in XML format and are typically sent over HTTP. Many existing commercial products natively support SOAP and the SOAP description file – called a WSDL – makes it easy to generate proxy objects for custom .NET applications. The Force.com SOAP API gives developers access to all out-of-the-box and custom APEX objects in their organization.
• REST API. The Representational State Transfer (REST) service style is quickly becoming the preferred way to create and consume web services. REST services embraces the architecture of the web and relies on defining representations of resources that are typically transmitted via XML or JSON over HTTP using a standard interface (e.g. GET, POST, PUT, DELETE). Force.com provides a rich RESTful API that makes it easy for developers to interact with all the objects in their Force.com organization.