What is a computer virus?

  • A computer virus is a program designed to spread itself by first infecting files or hard drives and then making copies of itself.
  • Viruses spread by infecting other programs, either on the same computer or on other computers connected to it over a network. Any newly infected programs/computers will try to infect even more.
  • Pure data files are safe.
    • This includes graphics and sound files such as .gif, .jpg, .mp3, .wav, etc., as well as plain text in .txt files.
    • For example, viewing picture files will not infect your computer with a virus. The virus code has to be in a form that the computer will actually try to execute, such as an .exe program file or a Word .doc file
  • Viruses usually operate without the knowledge or desire of the computer user.
  • Viruses are software programs; the actual effect of any particular virus depends on how it was programmed by the person who wrote the virus. Some viruses are deliberately designed to damage files or otherwise interfere with your computer's operation, while others do not do anything but try to spread themselves around causing damaged files and other problems.
What are some general tips on avoiding virus infections?
  • Install antivirus software from a well-known, reputable company, UPDATE, and USE it regularly. New viruses come out every single day; an antivirus program that has not been updated for several months will not provide much protection against current viruses.
  • Install an 'on access' scanner (included in most good antivirus software packages) and configure it to start automatically each time you start your system. This will protect your system by checking for viruses each time your computer accesses an executable file.
  • Virus scan any new programs or other files before you run or open them, no matter where they come from. There have been cases of commercially distributed CD-ROMs and USB/Flash drives spreading virus infections.
  • Watch out for executable files unexpectedly received as attachments to E-mail. If you feel you must open the file first save the attachment and then check it with an up-to-date virus scanner before opening the file.
  • If your E-mail has the ability to automatically execute JavaScript, Word macros, or other executable code contained in or attached to a message, it is strongly recommended that you disable this feature.
  • Do regular backups. Some viruses will erase or corrupt files on your hard drive, and a recent backup may be the only way to recover your data. Ideally, you should back up your entire system on a regular basis. If this is not practical, at least backup files that you can not afford to lose or that would be difficult to replace: documents, address books, important E-mail, etc.
What do I do if I get a virus infection?
  • If you have not used a good, up-to-date antivirus program on your computer, do that first. Many problems blamed on viruses are actually caused by software configuration errors or other problems that have nothing to do with a virus.
  • If you do get infected by a virus, follow the directions in your antivirus program for cleaning it. If you have backup copies of the infected files, use those to restore the files. Check the files you restore to make sure your backups were not infected.
  • For assistance, check the web site and support services for your antivirus software.
What is the best anti-virus software available?

Adapted from