This is one of the subjects explained in ArticSoft's Security Education Center - www.articsoft.com/security education.htm and is very informative. This is one of the best security education sites I have come across for clear and concise articles. The beginners guides on encryption and passwords were especially useful. In addition, everyone should try out the SSL spoofing demo - and I used to think the padlock icon on showing on my browser meant my credit card details were safe! This site also provides useful links and security news items.