What is "ajax"
AJAX means Asynchronous javascript and xml.
Although not a technology in itself, AJAX is a term coined in 2005 by Jesse James Garrett, which describes a "new" approach to using a number of existing technologies together, such as: HTML/XHTML, CSS, Javascript, DOM, XML, XSLT, and most importantly an object XMLHttpRequest. AJAX uses the API [XMLHttpRequest] (Abbreviated XHR) to manage HTTP requests from within code.
When these technologies are combined in the AJAX model, web applications are able to make fast, incremental updates to the user interface without reloading the entire browser page. This makes the application faster and more sensitive to user actions.
This communication is performed by Javascript code in the browser. It was originally intended that the data would be encoded in XML form, hence the acronym AJAX. However, the term is now used for all server browser interaction of this type, even when XML is not used.
Although the X in AJAX means XML, json (Javascript Object Notation) is used more than XML today because of its many advantages, including the availability of native methods to handle it, its lightness (compared to XML) and also being a strict subset of Javascript. Both JSON and XML can be used for information packaging in the AJAX template.
[XMLHttpRequest] is the main method of interaction between the server and the client, which is supported by all modern browsers. Early versions of Internet Explorer (5 and 6) do not support the native XHR API, although they support an Activex API that has most of the features of XHR (an example of this is new ActiveXObject ("MSXML2.XMLHTTP 3.0") ).