A computer is a local device that runs installed software directly on the machine, rather than inside a browser. This can be a desktop, laptop, or other general-purpose endpoint where programs have access to the operating system, files, network, and hardware resources.
In cyber security, the distinction matters because a computer often has a broader attack surface than a browser-only environment. Malicious software may try to install persistently, steal data from local storage, or use the device’s permissions to spread through a network. Defenders also rely on the computer itself for controls such as antivirus, endpoint detection, patching, encryption, and user privilege management. When software is delivered “on a computer,” security teams must consider how it is installed, what it can access, and how it behaves outside the browser sandbox.