How can a computer virus affect a system?

A computer virus primarily affects a system by adversely impacting its performance or potentially damaging programs. When a virus infiltrates a computer, it can consume system resources, leading to slower performance, crashes, and erratic behavior. This degradation occurs because the virus may run background processes that compete with legitimate applications for resources like CPU time and memory.

In many cases, viruses are designed to corrupt or delete files and programs, which can result in data loss and system instability. For example, a virus might overwrite critical system files or modify applications, rendering them unusable. Furthermore, some viruses replicate themselves, spreading to other files on the system, amplifying their negative impact. Thus, the damaging nature of a virus is what distinguishes it from beneficial software or system enhancements.