A social networking service is an online application
specifically focused on building and verifying social networks for a
specific purpose (whatever it may be). Many social networking services
are also weblog hosting services. With the currently growing interest in
online social networking services, social relationships in the real
world are emerging in the Web and a user itself is gradually coming to
play a central role in Web content. The emergence of user information
from the real world into the Web has a great impact on information system..