What is the definition of a virus in computer terms?

A virus in computer terms is defined as a program that can copy itself and infect a computer. This definition captures the essential characteristics of a virus: its ability to replicate itself and spread from one machine to another. Once a virus infects a computer, it can perform various malicious actions, such as corrupting data, stealing information, or compromising system performance.

The focus on self-replication is key to understanding how viruses operate. They exploit vulnerabilities in systems to spread, often through user actions, such as opening infected files or downloading malicious software from the internet. This behavior distinguishes a virus from other types of software, which may not have the replication capability.

Moreover, the other options describe different aspects of software that do not align with the characteristics of a virus. For instance, enhancing performance or improving user experience does not describe the destructive nature of a virus, while a security system is fundamentally aimed at preventing threats rather than being a malicious program itself.