Why do people share their lives on social networking websites like Facebook?

(From Quora: click here)

This  is nothing new. Until recently we used to share personal things only with close friends & family because of physical and social limitations (not because we didn't want to share it with others). Ever since the birth of civilization, we have always  wanted to tell others about what is going on with our lives. You can't keep calling 100s of friends to tell them about your pet nor can you go knocking on your neighbors door every time you look awesome in a party (although some people still do that). 

Facebook and other networking are like a huge bottle where everyone deposits their messages. It is now up to the people to: 

- read/respond to messages, if they are interested
- read it when they want to

In other words "Facebook & co." have removed physical/social limitations and given you the ability to stay in touch with 100s of people at the same time. To replicate this in the real world, all your friends and family will have to sit outside your office/home and wait for you to come out and talk to them (even then you will be clobbered with their responses).  

Is this good? I have written a couple of things on it: