Web traffic redirection is the steering of a browser request to a page other than the one the user intended to open. It can happen through malicious DNS answers, proxy changes, captive-portal behavior, injected HTTP responses, or compromised routing on a local network. In many cases the browser still appears to be working normally, which makes the trick effective.
In cyber security, redirection matters because it is often the first step in phishing, malware delivery, or credential theft. Attackers can send a victim to a fake login page, a fake software-update prompt, or a warning screen that encourages the user to run a file. Defenders look for unexpected domain resolution, certificate mismatches, forced portal pages, and network devices that alter requests. On public Wi-Fi, especially, redirection can exploit the trust users place in routine sign-in screens and push them toward attacker-controlled content.