XHR

Wikipedia is so wise: XMLHttpRequest (XHR) is an API available in web browser scripting languages such as JavaScript. It is used to send HTTP or HTTPS requests directly to a web server and load the server response data directly back into the script. The data might be received from the server as XML text or as plain text. Data from the response can be used directly to alter the DOM of the currently active document in the browser window without loading a new web page document.