I have during my college days used XMLHttpRequest object and its equivalent in Microsoft world to make Ajax calls and those Ajax calls were to the URL within the same domain. But with the advent of Webservices and whole lot of mashups being developed, Ajax calls are not restricted to same domain but the cut acorss different domains. When this cutting across domain boundaries happens making Ajax calls using XMLHttpRequest fails due to security enforcements implemened by the browsers. That’s when the idea of JSON-P i.e JSON with Padding came up.
In this post I will quote from different sources about JSONP and then go ahead and implement example which invokes Stackoverflow API to retrieve the unanswered questions tagged ‘jsonp’