Before you begin to search in social networks, try to enter a query about a person in any search engine. It can be www.google.ru, www.yandex.ru, www.yahoo.ru etc. there are cases of indexing by search engines of open pages on the portals of employment. It's possible that entering your name and the name of the desired person, you will get about him even more information than expected.
The social network Facebook (www.facebook.com) should look for "advanced" Internet users, whose average age is 25-40 years; bloggers; people living abroad. But it is worth considering that with the release of the 2010 film by David Fincher "the Social network", Facebook ranks were replenished by users who only begin to master communication in the virtual space.
Network "In Contact" (www.vkontakte.ru or www.vk.com) for many years unites active young people who grew up with a mobile phone in one hand and a notebook in the other. "Contact" is to search pupils, students and those who recently graduated. However, not every user is a "Contact" points when you register your real name. However, this also applies to users of all other networks.
As for the portals "Classmates" (www.odnoklassniki.ruand "My World" (www.my.mail.ru), here you can find members of the older generation. In the case of "Classmates", the reason for this is the popularity of the resource among those who wish to communicate with old friends and acquaintances. In "My world" as people in the age recorded by and large due to the popularity of the postal service Mail.ru of direct relevance to a social network "My World".
To search in one of the social networks, you must have a user account on it, you can always get for free in a few minutes.