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You've probably been sick before. It's not fun. In many cases, like the flu, you're sick because of a virus. Tiny germs ready to multiply and spread from person to person, via handshakes or sneezes. Computer viruses are no different. Instead of germs, they are computer programs. These programs are usually designed by criminals to multiply and spread from computer to computer like a disease. If one makes it to your computer, it can erase your files, send emails without your permission, or even communicate sensitive information to criminals. Let's take a closer look, because what we call computer viruses can actually be viruses, worms or trojans.

We’ll start with viruses. These bugs hitch a ride when something like a file is shared between computers. This often happens via attachments sent in email or shared USB drives. Once someone clicks to open the file, the damage is done. The virus is now on that computer, where it starts to multiply and look for chances to hitch a ride to a new computer. Like a sick human, it’s sometimes hard to tell when a file has a virus. For this reason, the best defense is anti-virus software. It prevents viruses from getting to your computer and removes them when they are found.

Now, worms are a little scarier. They are programs that spread to computers without humans doing anything. Criminals create worms to spread via computers that are connected in a network. They worm their way from computer to computer automatically whether it's a small office or a global network like the Internet. Usually, the worms find a back door, a way to trick the computer’s software into letting them in. Once they're in, they look for the same back door in similar computers, wreaking havoc along the way. The best defense from worms is keeping your computer software up to date at work and home. This helps close the back doors and prevent problems.

Trojans, our last example, are sneaky bugs. Like the real trojan horse, they’re a trick. If you fall for it, you end up downloading a virus from the Internet. It may appear to be a game or useful software, but hidden inside is a program that can cause real problems.

For example, these programs can open new back doors, giving criminals access to your computer and information over the web. Not fun. To avoid trojans, only download software from sites you trust. Just like washing your hands and covering your cough, you have to be aware of what causes problems to avoid them. Keep your computer up to date and get anti-virus software. It will help prevent problems and help you recover. And please don't click on links, attachments and downloadable files unless you know they're legit. Through a little awareness, you and your computer can stay happy and healthy.