What is JSONP?

JSONP (JSON with Padding) is a communication technique used in JavaScript programs running in web browsers to request data from a server in a different domain, something prohibited by typical web browsers due to the same-origin policy. JSONP works by embedding a `<script>` tag in the HTML page. The script source points to a URL on the external domain that returns JavaScript code, not plain JSON data. This JavaScript code consists of a function call, with the JSON data as the function's argument. The function name is provided as a query parameter in the URL request, effectively allowing the external server to 'pad' the JSON data with the function call. The web page must define this function beforehand, allowing it to handle the received data. JSONP is primarily used for read-only data retrieval (GET requests) due to its reliance on `<script>` tags.