I’m in the midst of preparing a presentation about how the Internet space has changed over the last five to six years. To be as realistic as possible, rather than just roll back some of our data to 2005-2006, I opened my presentation archive and read through some of my decks from that timeframe.

A PowerPoint file from the summer of 2005 focused on online video. There appeared to be a gaping hole in my survey of the online video landscape – no mention of YouTube (of course it hadn’t launched yet).  That’s when it hit me – I remembered how confident that I was in my prediction that Google Video would continue to own the Hitwise Entertainment-Multimedia category.

Another chart in the same presentation showed how MySpace was the 800 lb. social marketing gorilla, more than six times the size of nearest competitor Facebook, of course we all now how that story played out.

So today, when asked if Facebook will continue to dominate social networking, or if Groupon is worth $6 billion dollars, I’m not as quick to answer. The more you study observed Internet behavior, the more you realize how quickly things can shuffle.

So what’s a digital marketer to do in an environment of constant change? The answer is to arm yourself with as much data as possible. This year’s Digital Marketer report would be a great start.

Want to learn more about other purchase decision influencers? Click here to request a copy of Experian Marketing Services highly-anticipated 2011 Digital Marketer Report, launching in late March. The report features an editorial by Bill Tancer as well as unreleased data spanning email, social, mobile, search and more.

The 2010 Social Networking Report provides the hard data behind this consumer revolution, including the fact that fully 66% of online Americans use social networking sites today, up from just 20% in 2007. Social networking is an increasingly addictive activity, with nearly half of those who access such sites (43%) reporting that they visit them multiple times per day. While users of social networking sites may have initially signed up to better keep in touch with friends, a growing number say they now use sites like Facebook to connect with family members. An astounding 70% of social networkers keep in touch with family via their various online networks, up from 61% a year ago.

Fully two-thirds of all online adults today have visited a social networking site in the last 30 days, up from 53% in 2008 and 20% in 2007. Social networks have most thoroughly penetrated the young adult market, as nearly 9-in-10 online 18-to 34-year-olds visit such sites today. But even older Americans are tapping into social networks, with 41% of online adults age 50 and older making monthly visits to sites like Facebook, MySpace and Twitter.

The rise of social networking tracks closely with that of Facebook. As of April 26, 2010, 46% of the U.S. online adult population reported having visited Facebook in the past 30 days.

While keeping in touch with others is an important part of social networking, the popularity of games like Farmville and Mafia Wars illustrate that fun is a big part of the appeal of social networking.

Whether it’s keeping in touch with others, playing games, debating politics or any of the other reasons people use social networking sites, it cannot be denied that there’s a sense of addictiveness to it all. Visiting social networking sites multiple times a day is up 28% over last year, while less frequent visits are down across the board.

As social networking sites extend their reach across generations, Americans are increasingly using such sites to connect with more than just their friends. Today, 17% of social networkers communicate with their parents via those sites and 22% connect with their kids, up from 9% and 15%, respectively, a year ago.

An astounding two-thirds of social networking site visitors (68%) say they have shown their support of a product, service, company or musical group by becoming a “fan” or a “friend” on a social networking site. One year earlier, only 57% of social networkers had publicly declared their “like” for a product, service, company or musical group.

Knowing that social networkers are comfortable connecting with products and brands they support, it’s important to understand which brands have the best opportunity to connect with this group. Top retail brands among Facebook users, for instance, include H&M, Hot Topc and Forever 21. Specifically, Facebook users are full twice as likely as the average American adult to shop at H&M. Twitter visitors are 3.7 times more likely to shop at Nordstrom.

Heavy users of social networking sites are primarily concentrated in the Northwest and markets that are heavily influenced by major colleges or universities.