This document discusses JSON (JavaScript Object Notation) including its features, applications, and use cases. It provides examples of how JSON is used for data interchange between clients and servers, as a configuration format, and for data persistence in document databases like MongoDB. Specific applications mentioned include .NET Core using JSON for application settings, the JSON.NET framework, and Kubernetes API servers using JSON for communication. The document also discusses how JSON is used in the Physical Web concept to make physical devices discoverable and interoperable on the web.