AJAX is a browser technique for sending and receiving data in the background, without reloading the page. It combines JavaScript with asynchronous web requests, so a site can update parts of the interface while the user stays on the same page. Dynamic WordPress plugins often use AJAX for actions such as searching, filtering, saving settings, or loading content on demand.
In cyber security, AJAX matters because it often exposes server-side endpoints that can be reached from a public page. If those endpoints lack strong authentication, capability checks, or nonce validation, attackers may be able to trigger sensitive actions directly. That can lead to account creation, data leakage, or unauthorized changes. Defenders review AJAX handlers, validate every request on the server, and treat convenience features as attack surface, not just front-end code.