The social graph matters to marketers because knowing how social graphs work can makes ads and campaigns more effective, according to Debra Aho Williamson, senior analyst at eMarketer.

“By understanding the connections between people and how information spreads in a social network,” Ms. Williamson said, “marketers can tweak their messages to make viral spreading quicker/easier/faster.”

As Sean Ammirati of mSpoke noted on ReadWriteWeb this spring, our real social graph is far more complex than what is recorded on today’s social networks, and includes many colleagues, parents, extended family and neighbors.

Because online social networks do not capture the real social graph, tapping into those extended, real-world connections are important for marketers.

Even among Internet-using college students in the US—the heaviest social networks users—talking to friends and family still ranks highly as a way to learn about new products. An August 2008 study by Harris Interactive for Alloy Media + Marketing found that more than six out of 10 college students surveyed talked to friends to get the scoop on new products, and 38% talked to family.

Social media’s popularity will fill in some of the blanks in the social graph.

Profiles are generally expected to become portable so that consumers need only create one profile and use it in many places on the Web, making social networking a key online activity regardless of the performances of individual community sites such as MySpace or Facebook.

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