A “half-click attack” is an informal term for a web-based attack in which a person may be exposed to malicious content simply by loading a page, rather than deliberately downloading or installing something. The page may be reached through an advertisement, a redirect, or a compromised website. Exposure does not by itself prove that a device was exploited or infected.
In cyber security, this matters because browsers and the software that renders web content are part of a device’s attack surface. Attackers may serve exploit code that targets unpatched vulnerabilities, while defenders investigate redirects, page content, and browser telemetry to understand the risk. Keeping operating systems and browsers updated, and using available device security controls, can reduce exposure, though they cannot guarantee protection from every exploit.