One thing life has taught me: if you are interested, you never have to look for new interests. They come to you. When you are genuinely interested in one thing, it will always lead to something else.
Web services (sometimes called XML Web services) are software components that provide some type of service over the Internet. Just like a conventional Web site, a Web service is reachable through a public URL and is subject to the same security restrictions of an HTML-based Web site. Unlike ordinary Web sites, though, Web services don't have a user interface. Web services are programmable entities that expose callable functions.
The caller can certainly be a human, but it will more likely be ...