T he world of social networking is complex and constantly evolving. Here’s a look at it by the numbers:

1. As of 10 February 2009, Rotary International had 18,113 fans on Facebook.
2. Of the 40 million Americans who regularly log on to social networking sites, 60 percent use Facebook, 63 percent use MySpace, and 34 percent use both.*
3. In a typical week, social networkers on Facebook and MySpace connect one-on-one with an average of 18 people, usually by sending personalized messages to friends, leaving comments on friends' pages, or sharing pictures.*
4. The most common type of U.S. social networker is a single woman in her 20s who is either a student or employed.*
5. "Tweets" are Twitter posts of 140 characters or less.

*According to Netpop Research, Social Networkers U.S., 2008