Apps for mobile devices use web services. A good example is the Great Clips app. Great Clips is the world’s largest salon brand. It doesn’t take appointments. Customers receive service on a first come, first served basis. You can checkin online using the Great Clips app.
When you launch the Great Clips app a map displays showing the Great Clips stores near you. Each map pin shows the estimated wait time at that store. You checkin to a store by tapping on the map pin and confirming your visit. When you arrive at the store, your first name already appears on the list of waiting customers. If you timed it right, you’ll be the next in line.
Your smart phone and the computer at the Great Clips store used web services to make this happen. Any mobile app that retrieves information for you does so through the use of web services.