Social Sites and we

Friend and relatives old memories always mesmerism when we sit free and remember them know about there updates and show our update .Internet had made all these things a step away .But how long and how much activity should be there ?.How safe we are how much we enjoy ? how much we should spend time in it ?

What are social sites?
Sites which allow us to find our friends chat them ,show our picture videos and latest news despite of boundries.

Few Sites 
www.Orkut.com
www.facebook.com
www.Twitter.com

How to register?
Just log on to these sites with the basic gmail or yahoo ids.

How much to write and  share ?
Privacy setting always for friends .
Do not write too much details .
Regularly delete the photo .
Do not add unknown person.