Hello, I am curious about how some of the web interaction on iOS apps work. Let's say there is an app where you post a string of text and the text is tagged by location. Then another person on a different device searches for the name of that city and views the string of text posted by the other iOS device. Could someone explain what this is called or maybe even how this works? I'm not interested in building an app like this, but rather curious about the technology itself.