Keep in mind that not everything that goes wrong with a computer is caused by a computer virus or worm. Both hardware and software failure is still a leading cause of computer problems.
A virus is a program that reproduces its own code by attaching itself to other executable flies in such a way that the virus code is executed when the infected executable file is executed.
You can't get a virus just by reading a plain-text E-mail message or Usenet post. What you have to watch out for are encoded messages containing embedded executable code (i.e., JavaScript in an HTML message ) or messages that include an executable file attachment (i.e., an encoded program file or a Word document containing macros).
In order to activate a virus or Trojan horse program, your computer has to execute some type of code. This could be a program attached to an E-mail, a Word document you downloaded from the Internet, or something received on a floppy disk. There's no special hazard in files attached to Usenet posts or E-mail messages: they're no more dangerous than any other file.
