There are many different ways that computers can become infected with malicious software. Malicious software includes viruses, worms, trojans, spyware, adware, and other forms of malware. Some of these attacks take advantage of flaws in computer programs or systems. Others attack vulnerabilities in human behavior.

Malicious software can damage or destroy files, corrupt databases, steal personal information such as credit card numbers, and disrupt operations. Even worse, once a computer becomes infected, it can spread the virus to other computers. More info: What is email encryption