The main reason people keep getting viruses and spyware on their computers is that they're actually installing it themselves without realizing it. Malware (that's the umbrella term for such software) doesn't just sneak in and install itself most of the time - it needs to fool you into letting it in.
Outlined below are the five most common ways people accidently infect their computers. By using the accompanying information, you should be able to drastically cut your computer's infection rate.
1) No security software, or out of date security software.
Unless you're a computer whiz who could, if necessary, manually remove a virus from every nook and cranny of your computer, despite all of its efforts to operate with perfect stealth in your machine, you need security software. Norton, Panda, McAfee, and AVG are just a few of the many antivirus programs available to keep your computer safe.
Don't assume for a minute that you can let your guard down once you have security software installed, though. You'll also need to keep that software up to date. New viruses and other threats are coming out all the time, and your security software needs to know to look out for them, thus your software needs to get regular updates from its host company. Security software usually updates automatically by means of a product subscription which you may need to pay yearly for. Without updates, you'll only be protected from old viruses, not new ones.
Security software, even when up to date, can not protect you from everything. Your security software listens to you before it does anything, just as your private police force wouldn't disregard your orders. Therefore, if you download a program like "Antivirus 2009," an example of a virus disguised as security software, and permit it to be installed by clicking an "okay" button, your actual antivirus program will not prevent that installation. However, it will likely detect the virus you just installed the next time you do a scan.
In order to be safe from viruses and adware, you must keep both yourself and your security software informed and up-to-date.
2) Falling for email scams and emailed viruses
Some viruses invade the email address book of the infected computer and mail themselves out automatically to everyone in the address book. If this happens to one of your friends, you may get what looks like a friendly email from that person in your inbox, inviting you to click a link or open an attachment. If you have not discussed getting an attachment from this friend, do not open it! Reply to the friend and ask about the attachment. You'll likely be informing your friend of an infection he didn't even know he had!
Also keep an eye out for junk mail. Lottery scams, Nigerian "money transfer" scams, and advertisements for unfamiliar antivirus software are just a few of the scams you might get in your inbox. They may wnat to infect your computer, or they may just be emails attempting to convince you to send money in order to get money - money you will never receive. Use your junk mail filter to avoid even looking at most of them.
3) Clicking on popup advertisements
The World Wide Web has been mired, over the last year or two, with fake "rogue antivirus" programs. These programs are viruses, and they get installed in your computer by first confronting you with a popup. The popup will likely say that your computer has been scanned, that a ridiculous amount of viruses and adware has been found, and that you need to "click here" to remove them. If you click, it will install a virus, which will then attack you with many popups demanding money for the removal of viruses that aren't really there in the first place.
Often, these popups will not allow you to click away without clicking on them. If this happens, close the broswer window altogether.
Program titles to look out for are "Antivirus 2009," "Antivirus XP," "Antivirus 360," etc. They ar edisguised as known, legitimate antivirus programs which may already exist on the market. For legal reasons, they will not actually call themselves products of known legitimate companies, like Microsoft or Norton.
If you have a legitimate antivirus program installed, it will not send you popups in the middle of the screen. Rather, little popups will slide into view above your computer's clock. These warnings are likely to be legitimate.
4) Downloding unsafe software
Antivirus fakes aren't the only kinds of unsafe software out there. Also avoid downloading toolbars of any kind, since on top of slowing down your browser and internet connection, they're likely to contain adware and spyware. Also avoid games, Smiley Central, Zwinky, and free downloads in general.
If a program is free, there's likely some motivation for a company to give it away for free. That motivation is almost always the opportunity to install adware popups and spyware on your computer. This is usually legal, too, because permission is added into the terms of use agreement that every user must agree to before installing the software. That's right - it's in that long mass of text that no one ever reads.
5) Downloaded from unsafe sources, like file sharing programs
File sharing programs like Napster, Bearshare, and Limewire, as well as torrenting programs, can yeild nasty results. You could pick up all kinds of malware on there, retitled as the file or program you searched for.
At the same time, you probably don't want to give up filesharing. If you're not willing to give it up, try this: find the folder that your filesharing program stores its downloads in. Right-click it, or open it and right-click on your recent downloads. You should get the option to scan the file with your antivirus program. Do this very regularly, and always before using what you download.
With these five tips in mind, you should be able to avoid most, if not all, malware and viruses. Just in case you get another one, though, remember to back up your important files regularly. There's always a small chance that a bad virus might strike.