A malware virus takes its name from its health hazard namesake. And just like the biological version, a computer virus is designed to infect its host, which in this case is a computer system. It does this by replicating without a user’s knowledge or permission and injects its own code into whatever programs may exist on the system. Viruses can also spread to other connected systems through attachments. Typically, a file containing a virus or executable program will be shared. When it’s opened by another user, it will infect the next system, and so on, causing damage along the way. This can range from irritating popups to a total crash.