URGENT: What's the name of the laws regarding privacy on social networking sites?

[Dunbar Pappy ÏŸÏŸ]

These vary by what country. Europe currently has the more stringent laws, but in the US, much of what goes on is '"self regulatory" and that means 'anything goes'.

As "Urx..." points out, when you sign up for a service, you consent to their rules...which may supersede other 'regulations'.
Of special importance is to comprehend that almost all services modify their ToS & PP's whenever they feel the urge to augment their income.
Almost always these mod's to the original agreement you got on-board with, change to the detriment of privacy...never the opposite.
Facebook has a running history of betraying users, and making it almost impossible to follow what settings do what actions.
Look for Yahoo to make some significant changes December 1 of this year.

For some insight on these and other issues, see the "Electronic Frontier Foundation, who monitor these very things:
https://ssd.eff.org/