JSON (JavaScript Object Notation) is a data format that is non-proprietary, human-readable, easy to parse, simple to generate, and widely adopted. You can read more about JSON at the project website here http://www.json.org/ Some of you might be saying, wait there is another data format with the same properties, namely XML, why bother with JSON? For me there are two reasons for data JSON is superior to XML. First, it is designed for data so handles things such as arrays much more eloquently than XML. There are versions of XML better suited for Data than the generic flavor but on the whole, XML is trying to provide a flexible structure to describe complex metadata not be a simple format for data. Second, there is only one type of JSON whereas XML can come in endless variety.  It is XML’s flexibility that is both its asset and liability. By being flexible XML can be used in a variety of ways but because of this confusion often arises about exactly how to consume and generate data. One of the things XML was supposed to solve. When transferring data I do not like ambiguity, I want strict conventions.

A great article about XML verse JSON with good comments is found here, http://ajaxian.com/archives/json-vs-xml-the-debate.

But I use JSON not because it is better for data (there is always something better) but mainly because a lot of data I want to consume uses the JSON format and you can load it directly into R: http://cran.r-project.org/web/packages/rjson/index.html

Below is an example of a JSON formatted dataset:

"CustomerId" : 1,
"age" : 23,
"name" : "Joe"
"CustomerId" : 2,
"age" : 45,
"name" : "Mika"
"CustomerId" : 3,
"age" : 34,
"name" : "Lin"

You can see that it is human readable. {} enclose rows and a row/column is expressed as “Colname” : value.