These days people tend to worry more about their computer catching a virus than they do about catching one themselves and with good reason. After all, most viruses that infect humans only cause a cold, and in a week or so, that infection clears on its own. But if your computer gets infected, that’s a whole other story!

So what are these nasty little critters that wreak havoc on our computers? Computer viruses are essentially small software programs that spread from one computer to another by copying themselves and infecting the computer, usually without you even realizing it. Viruses are passed on from one computer system to the next when:

• You send files from an infected computer over a network.
• You transfer files from an infected computer to another one via floppy disk, CD or USB drive.
• You open an infected email attachment.
• You accept an instant message or photo from someone whose computer is infected.
• You surf untrusted Web sites and either download, or are infected by, malicious content.

Once you catch a virus, it usually becomes obvious pretty quickly since most viruses are designed to cause your computer to run amok. Other times you might not be as fortunate to notice the virus immediately. A virus may just park and wait for something to set it off, or covertly steal your data over the course of time.

If you do notice the virus immediately, you’ll soon detect corrupt files, error messages or deleted files. Some viruses may even erase your entire hard drive! Other viruses will damage certain computer programs, or replicate themselves and send infected emails to everyone in your address book. Viruses will also take up large portions of your computer’s memory, causing irregular behavior and system crashes. A lot of viruses also contain inherent software glitches that may also lead to system crashes and file deletions.

So who would ever want to create such horrible mechanisms? Computer programmers write viruses, as well as others who produce them using virus creation software. Virus writers have various motives. Some write them as part of research projects, or to spread a certain political or social message. Others do it for the fun of it, or as a form of vandalism. Some people target companies they have a beef with, and others design viruses to steal personal information that could be used for identity theft. Occasionally some people write “good” viruses, which are intended to improve the programs they infect, or get rid of other bad viruses. However, these “good” viruses can also go bad by attempting to fix the wrong file or deleting a file mistakenly.

Once your computer has been infected, it is sometimes a long, difficult process to get rid of the virus completely. That is why the best medicine is prevention. If your systems do get infected, the best action is to call in experts to make sure you have your bases covered.