What really is "Twitter" and "Face Book"? How does it work?

[Inundated in SF]

"Twitter is a service for friends, family, and co–workers to communicate and stay connected through the exchange of quick, frequent answers to one simple question: What are you doing?" And I think you can "chat" in real time (that is, the person/people logged into the page can see what you are typing as you type and can respond immediately--sort of like texting I would assume).

Facebook, to me anyway, is just another way to expose yourself to a whole bunch of strangers, to promote yourself, to divulge more information then is wise. I use Facebook to spy on my nieces and nephews to see what they are up to (because they forget that anyone can lurk around without announcing themselves and read their page--and when my nephew told his mom & dad "please don't sign up with Facebook, respect my privacy", although they are respecting his privacy, I can go read his page. I also have a niece who travels to a lot of underdeveloped areas and I can keep up with her doings by logging into her page. I however never post on Facebook, I'm just peeping.