The Force.com Web Services API provides access to your Force.com data and logic. You can call the Web Services API from a wide variety of client-side languages. All of the functionality built into the Force.com on-demand platform is automatically part of any application that uses the Web Services API. Data validation, workflow, Apex triggers and the Force.com security scheme are just a few of the features that help you to integrate your external application with the Force.com platform. Prabhavat team has extensively used the Force.com WebService API to integrate external data into sales force.