Facebook recently (in December, 2009) unveiled a radically revamped 
set of privacy controls. They are better and more forward-thinking than 
its previous efforts, but Facebook made one very important change in 
late 2009: almost all user data is now made public by default.
Facebook users were asked to verify their privacy settings using 
Facebook's "Privacy transition tool" that recommended some default 
settings. Oddly, the suggested defaults made most profile settings, 
photo uploads, status updates and application settings viewable by 
everyone on the internet. This means the whole world could see 
everything Facebook users post if they didn't change the defaults.
For more details on these privacy changes, see the Electronic
 Frontier Foundation's overview.
The most invasive part of the policy for most people will be the 
public search results settings. This means if they post something and 
later decide they want to switch to a private profile, those 
embarrassing posts will remain in search engine indexes.
The good news is that Facebook actually now offers more 
fine-grained controls over which bits of personal information you share 
than ever before. The bad news is that the high level of control makes 
preserving your privacy a fairly complex process. There isn't a simple 
check box that says "make my profile private." 
But fear not, we've got you covered. Follow these instructions 
below.