# Anatomy of a Request I was asked to provide an simple explanation of how an iPhone App interacts with, and retrieves data from, a web service, such as we use at Hotels.com. It seems to have been really helpful for some non-technical people here, and so I thought is might be helpful for others. Created on my journey home one day, using [OmniGraffle for iPad](https://www.omnigroup.com/omnigraffle/ios). ![Anatomy of a request diagram](../../images/tumblr_files/tumblr_m58pauizt01r4drs9o1_1280.png)