Help: explanation of secure flash?

[rhkramer@gmail.com]

I've seen warnings (against hacks) that say (among other things) to enable 
"secure flash".  I've been googling to learn more about that, but I haven't 
found any good explanation.

I'm beginning to get hints that it is not so much a thing (to be enabled), but 
more the (a) process to update the computer's BIOS.  (e.g., "'Unable to start 
a Secure flash session' error message.")

Can somebody provide either a little more explanation and / or a link to a 
(reasonably simple) reference?