Bibliography

1. http://searchsecurity.techtarget.com/definition/firewall
   
2. http://searchsecurity.techtarget.com/definition/antivirus-software
   
3. https://www.computerhope.com/jargon/u/update.html
   
4. http://smallbusiness.chron.com/ways-safeguard-computers-45589.html
5. http://searchdatabackup.techtarget.com/definition/backup