JSON (JavaScript Object Notation) is a text-based human-readable format for data. It is designed to be language independent, but the syntax matches JavaScript (also similar to C). JSON is very convenient for parsing in the game's scripts using SpiderMonkey's builtin JSON.parse(). The game uses JSON (.json) files for storing raw data, when the overhead of a script is not required. Currently they are used for:

• Civilization data (civs\)
• Random map definitions (maps\random\)
• AI definitions (simulation\ai\)
• Assorted data shared by game setup and Atlas (simulation\data\)

For more information, see ​http://json.org/.