Amazon Marketplace is Amazon.com's fixed-price online marketplace that allows sellers to offer new and used items alongside Amazon's offerings, and customers to buy those items directly from the third party sellers using amazon.com's infrastructure. It is available on Amazon sites in over 60 countries, although not all sellers choose to ship internationally. Amazon.com charges your credit card and forwards your payment to the seller but does not pass along your credit card information.
Sellers may sell using an Individual Amazon.com sellers account or a Professional Sellers account for an additional monthly subscription fee. Individual Accounts may add a Pro-Merchant Option; Professional Sellers are required to have the Pro-Merchant Option. The Pro Merchant account is $39.99 a month and eliminates the .99 per item sales fee, allows the use of Amazon.com's order management tools, and allows the seller to list products that are not currently available on Amazon.com. (All other sales fees still apply, whether or not a seller is a Pro-Merchant—a percent commission and a flat rate variable closing fee).
See also 
- Amazon tax - information about paying sales tax as a seller or as a buyer