Which term describes the technique of requesting and reusing data using the XMLHttpRequest object with HTML pages and CSS?

• A. XML
• B. AJAX
• C. DOM
• D. JSON

Answer: (B)

The technique of requesting data from a server and updating parts of a web page without reloading is AJAX. It uses JavaScript to send asynchronous HTTP requests via the XMLHttpRequest object (and today often the fetch API), receive a response, and then update the page’s content by manipulating the DOM. This makes HTML pages feel more dynamic and responsive while still leveraging HTML for structure and CSS for styling. While the response data may be XML or JSON, the defining idea is the asynchronous data exchange and partial page update, which is what AJAX represents. XML is just a data format, DOM is the API used to modify the document, and JSON is another data format sometimes used with AJAX, but they describe data or the document model rather than the technique of fetching and reusing data itself.