Here’s a little-known secret about the online marketplace: how did Amazon and eBay get so big so fast?

Yes, they used venture capital to buy multi-million-dollar Super Bowl ads. And word of mouth did help tremendously, as did the slow response from many traditional brick-and-mortar retailers.

But what most people don’t realize is that Amazon’s and eBay’s growth was driven by affiliate marketers. These online middle men (and women) linked their sites to these big online retailers. Unlike Google Adwords’ pay-per-click (PPC) ads, these affiliate links did not pay a few cents per click. Rather, these affiliate merchants paid a percentage or sizable flat rate for each product sold.

Today, practically any business that sells on the web tries to harness the power of the affiliate marketing community. There are now literally hordes of affiliate marketers working from home and earning six-figure paychecks from their targeted websites.

The great advantage of affiliate marketing for merchants is that they get others to shoulder the cost of marketing their products. The individual affiliate marketers will create the web pages, drive the search engine optimization (SEO) and invest in PPC advertising to generate the traffic, leads and sales for the merchant.

So if you’re a fledgling online business with something to sell, how do you get in the game. You could do it the hard way and try to recruit individual affiliate marketers, but that can be very difficult — especially if you’re not sure how to price your commission structure.

A better way is to join affiliate networks. I met one of the fastest growing affiliate networks at two recent online marketing conference: www.ShareASale.com.

The offer much more affordable on-boarding for most merchants, especially when compared with other brands. Plus they actively train and motivate their individual marketers to really promote merchant products. There are, of course, many more out there, but ShareASale.com is arguably one of the best I’ve found.