Pros
More than anything else, social sites provide better ways to keep in touch with our classmates, friends and family. Even though we are from them, you and these people both have easy access to how each other is doing, as you can send messages as well as upload photos and videos.
Creating your network of contacts goes beyond geographical and cultural differences as you get to know and meet people who share your interests from almost all sides of world.
This one is tricky, but I choose to include it on the affirmative side. Online business people use these social services as tools to promote their websites, products and services basically because of the overwhelmingly significant number of people that they have brought together to form communities.
Cons
Identity theft and fraud are two bothersome concerns that have come out of social networking sites. The e-mail address, name, location, age, and many others are personal information that users give out, and others can use them in performing illegal activities. There are also people who pretend to be somebody else and convince you that they are in for a business deal. But, the truth is they are there to rob you out of your money.
Cases of online harassment and stalking have also been a concern. People who have issues with you or for whatever reason just can search on your name and stalk or harass you. In order to address this, users are allowed to report or block users that go out of bounds.
(Accessible on http://hubpages.com/hub/Pros-and-Cons-of-Social-Networking-Sites)
