The odds of downloading one of these computer viruses over the Internet have increased dramatically recently. Typically, you contract a virus by opening e-mail attachments.
Some viruses are relatively harmless to individuals.
They just attach themselves to outgoing messages or e-mail themselves to all the people listed in your address book. The sudden flood of e-mail overwhelms mail servers, causing the system to crash. Other viruses are more destructive and may lie dormant until a certain date. Then they spring to life to do their dirty deeds. Sometimes a strange message may appear on your screen or data and programs may be modified.