Today, I am parsing a document, which I coincidentally wrote as {'status':'ok'}. I spent lot of time checking browser requests and setting proper header and content-type to application/json.<p>Then, I remembered that somewhere I read that it accepts only double quotation mark. so I changed that to {"status":"ok"} and it worked like charm. Later I confirmed that from json.org also.<p>So, my question why only one quotation mark (i.e. " ) was supported by json? what were historical reasons for that.