Ding, ding, ding! The battle is on, with email in one corner, and SMS across the ring. Which channel is best for your marketing efforts? Some 74 trillion emails are sent every year, and "only" 8 ...

But who are they? What do they do? How do they make money? And what makes someone a social media influencer? An infographic published by influencer marketplace Izea answers those questions—and more.