You can update the profile with your education and job details and a summary.
Additionally, you can also give and receive recommendations from co-workers and bosses.
Once the friendship is confirmed all the people in your friends' Friend Space become part of your network.
In that sense, everyone on My Space is in your Extended Network.
You can build your network of contacts, and invite others to receive your Tweets, and can follow other members' posts.
Twitter makes it easy to opt into or out of networks.
To start using Linked In you need to register and create a profile page.