I\'ve looked on wikipedia and Googled it and read the official documentation, but I still haven\'t got to the point where I really understand what JSON is, and why I\'d use
In the Java context, one reason why JSON might want to be used, is that it provides a very good alternative to Java's Serialization framework, which has been shown (historically) to be subject to some fairly serious vulnerabilities.
Joshua Bloch discusses this in depth in Item 85 "Prefer Alternatives to Java Serialization" (Effective Java 3rd Edition)
Java's Serialization was initially meant to translate data structures into a format that could be easily transmitted or stored. JSON meets this requirement, without the serious exploits referred to above.