The growth of social networks significantly contributed to the effectiveness of viral marketing.
As of 2009, two thirds of the world's Internet population visits a social networking service or blog site at least every week.
Facebook alone has over 1 billion active users.
In 2009, time spent visiting social media sites began to exceed time spent emailing.
A 2010 study found that 52% of people who view news online forward it on through social networks, email, or posts.