How safe / unsafe is Free Open WiFi?

["BlogPatrol.com" <cybersecurity () blogpatrol com>]

Hi, 

I have what is probably a rather basic question:  Just how safe are free, or open, WiFi networks that you find in 
Internet cafes, Hotels, Airports, etc?  My personal opinion is that there are very unsafe, but I do not have the 
technical expertise to explain to my colleages why they are unsafe.

Can anyone provide a summary, or a link to an article that provides a summary, of why a laptop or PDA user should avoid 
using free and open WiFi networks?

Regards,
Tony Nguyen

Tony Nguyen, President
BlogPatrol.com, Inc.
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