Traffic interception is the capture or observation of data moving between a browser and a website. It can happen at the network layer, through a proxy or rogue Wi-Fi, or inside the browser itself through an extension or injected code that sits between the user and the destination. Because modern web sessions are usually encrypted with HTTPS, interception does not always reveal full content, but it can still expose metadata, session tokens, requests, and other sensitive signals.
In cyber security, traffic interception matters because it can undermine privacy, steal credentials, and redirect users to malicious infrastructure. Attackers use it in man-in-the-middle setups, malicious browser add-ons, and compromised endpoints, while defenders may use controlled interception for inspection and filtering. Practical protections include enforcing HTTPS, checking certificate warnings, limiting high-risk browser permissions, reviewing proxy settings, and monitoring for unexpected traffic rerouting.