Before GeoJSON, there was JavaScript Object Notation (JSON), and before JSON, there was Extensible Markup Language (XML). As computers started to talk to each other over the Internet, the ability to send data from a service to a client became more important. XML, JSON, and GeoJSON are formats that represent and transmit data. XML was an attempt at a human-readable format that could store and send data. XML uses opening and closing tags to separate data. JSON is an alternative to XML that more closely resembles the way objects are created in JavaScript. JSON uses key-value pairs and is usually smaller than XML.