An API, in the context of this book, is a publicly available web-based service that returns data, likely in JSON or XML formats. Many iOS apps work with APIs to access JSON files, which are then used to provide the app with data. You will not be learning about how to connect to an API at this point. Instead, you will use JSON files downloaded from http://opentable.herokuapp.com, which have been updated by Craig Clayton for this book. As you will see, working with a JSON file is similar to working with .plist files.

Let's study the JSON format next to see how it stores data.