The overall term for software that harms your computer is “malware.” If you paid attention in Latin class in high school, you might remember that “mal” is a prefix that means “bad” and “ware” simply refers to any type of computer program.
The second-most-popular term that gets thrown around is “virus.” A virus is pretty much the same as its biological counterpart, but on the computer. Like the common cold, a computer virus attaches itself to files on your computer, replicates itself, and spreads itself out to as many computers as possible. Nasty! Since it is hard to see like the common cold virus, it can attach itself to the hidden parts of your hard drive, system files, or even random files that contain data valuable to you. These spread through executable files… If you see a file that ends in “exe” beware, if you are not sure where it came from, don’t open it! It’s maybe a virus. To be safe you should run a scan on it, like MalwareBytes.
“Spyware” is another common term that people use a lot. Spyware does what it sounds like – it spys on you. It will find your information without you even knowing. Spyware can arguably do the most amount of damage to the everyday computer user. It can discover your credit-card information, SSI and/or other personal info that can be used by the hacker. Sadly, it can go undetected for a long time – that’s just how sneaky it can be. Side note: Be aware that not all anti-virus software can catch spyware though, as the code that it uses is significantly different from traditional viruses. So again use a spyware/malware scanner like MalwareBytes to regularly check up on it.
ScareWare is new to the bevy of malware. It can disguise itself as something legitimate, but it tricks you. For example, the resent “Microsoft” scam, it will trick you into downloading something that looks like an antivirus, and then tells you that you have hundreds of viruses which you have to pay to remove. You get scared of course, give them your credit card to clean off the infection and bam… Chances are that the only virus is the program that is telling you that you have a virus! The best chances for removing this virus, if your other programs haven’t caught it, is simply to Google the name of the software and see how to remove it. Many security programs haven’t quite figured out how to deal with these yet. Your best defense is simply not to download any programs that you can’t verify are legitimate. But if none of these help, call in a pro, and call your local computer repair expert for help.
There are of course many other types of viruses, but the methods for protection essentially remain the same: practice safe browsing, and keep your antivirus updated.