In practice, a Web service commonly provides an object-oriented Web-based interface to a database server, utilized for example by another Web server, or by a mobile app, that provides a user interface to the end-user. Many organizations that provide data in formatted HTML pages will also provide that data on their server as XML or JSON, often through a Web service to allow syndication, for example, Wikipedia's Export. Another application offered to the end-user may be a mashup, where a Web server consumes several Web services at different machines and compiles the content into one user interface.
Like Flickr, 500px is a popular social network for photographers looking to share their best photos. It doesn't exactly compare to some of the alternatives discussed above because unfortunately, you can't directly link to photos if you want to share them elsewhere, but it's a fantastic option for photographers looking to show off their work and maybe make a little money from it.
You can build a profile on 500px, and photographers can sell usage of their photos through the site. However, you can’t directly link to photos on other websites. If you’re looking for a platform to upload photos to share on social media or other sites 500px probably isn’t the best option for you. The primary benefit of 500px is the opportunity to display your work and network with other photographers.