Web services typically let an application make requests over the Web, and rather than getting the data back as an HTML document, the data is returned as XML. This makes it very easy for the application to consume the information. Web services have emerged as the way that applications communicate with each other. In some cases, legacy back-end systems are wrapped with Web services in order to easily expose their data and functionality to the rest of the company. In other cases, Web-based providers (such as those listed above) add a Web service to allow programmatic access to the data and functionality that they currently provide to Web browsers.