This question posting is make me curiousity about the social network platform , How to make facebook, Twitter and Linkedin, with some knowledge about programming language, I thinks there is way to make facebook, twitter and linkedin, and other social networks, but it is difficult to make that application social networks alone, it is need a some small team to develop this application social networks, social network is become popular now because it can make one people communication with another people at this world, and I think it is very interesting application , what is feature common at social network , I can list :
common features:
1. Inbox,Outbox, and Sent (this is email common platform likes gmail, yahoo, msn)
2. Chatting (like Yahoo messangers, Windows Live, Skype) but this application chatting include at the social network
3. Some chemicals application to make friends, like at facebook is add friends, at twitter is like followers or followings
4. Search Form ( this is most powerfull feature I think at others application must have this Search form too) likes can search friends, or collegeus, or group, or company ( at linkedin)
5. Update Status ( this is must have this features)
6. Creating Group, Members or some questions

There is some common feature I thinks must have at the social networks , what do u think about this common features