If you want to create an online marketplace which is similar to Amazon or Etsy.com it would be a good idea to do a little research on the websites first. Both the sites Amazon and Etsy allow different sellers to post items they wish to sell and after the item is posted online, a buyer will select it, and pay the admin directly for the provided services. In this way, the admin makes his profit.
Multi vendor or seller shopping cart software will help you in personalizing your website to such an extend that it might appear similar to the above mentioned sites, but customized to however you see fit. When you select a multi vendor or seller shopping cart to create an online marketplace the there are various advantages. With more than one vendor at your every beck and call, you would be able to direct them how to sell their products. The admin basically controls all.
The shopping cart software also helps the vendors to communicate with the sellers and tell them to sell an entire set of products. Sites such as Amazon and Etsy.com use similar technology to keep their business running, and now you can also do the same with an efficient shopping cart software.