What is JSON?

JSON (JavaScript Object Notation)

JSON (pronounced like the English given name Jason) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition - December 1999.

JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

JSON's simplicity has resulted in its widespread use, especially in Ajax. In JavaScript, JSON can be parsed trivially using the eval() procedure. This was important for the acceptance of JSON within the Ajax programming community because of JavaScript's ubiquity among web browsers.

JSON is built on two structures:
A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.

Comparison to other formats

XML - XML is a markup language. JSON is not a markup language. JSON is a data interchange format. Both lack a rich mechanism for representing large binary data types.

YAML - Both YAML and JSON are data interchange formats.
Some of the limitations of JSON are addressed by YAML. Although YAML is significantly more complex it is still significantly simpler than XML.
It has been observed that JSON is a nearly functional subset of YAML. YAML parsers can be used to handle most of JSON. This occured by coincidence and not by design, YAML and JSON were conceived mostly in isolation of each other.

more details visit http://www.json.org/