XHR - XML Http Request All browsers have a built-in XMLHttpRequest Object (XHR). XHR is a JavaScript object that is used to transfer data between a web browser and a web server. XHR is often used to request and receive data for the purpose of modifying a web page.
HTTP is a protocol for fetching resources such as HTML documents. It is the foundation of any data exchange on the Web and it is a client-server protocol, which means requests are initiated by the recipient, usually the Web browser.