What is a computer virus known for?

A computer virus is well-defined as a destructive program that can be secretly loaded onto a computer and executed without the user's knowledge. This type of malicious software is designed to replicate itself and spread from one computer to another, often causing damage to system files, corrupting data, and impacting overall performance. The critical aspect of a virus is its ability to operate stealthily, making it difficult for users to detect until problems arise.

In contrast, options like performance optimization software, protective software, and presentation tools serve entirely different functions. Performance optimization programs are intended to enhance system efficiency, protective software is designed to secure data against threats, and tools for creating presentations focus on designing visual content. Each of these does not possess the malicious or self-replicating characteristics that define a computer virus. Thus, the correct understanding of a computer virus lies in its nature as a harmful program that operates covertly.