There are numerous reasons why you should buy antivirus software. One of them is that the majority of malware programs are created by hackers who are trying to get hold of your personal information so that they can steal it for their own use. The most common types of threats include spyware, adware, malware, and viruses. No antivirus program can protect against every type of threat. There are always exceptions, but using a good one will keep your computer safe from most of the common malware.