Online retail, the process of selling products online and on mobile through shops, 3rd party marketplaces like Amazon and EbayAn ecommerce giant, auction site Ebay allows retailers access to a market of buyers. Sellers pay a listing fee and a percentage of the sale of the item on Ebay, with the option to auction or set a Buy It Now price. Ecommerce sellers often use Ebay as an alternative 3rd party marketplace, in addition to selling through their own site., and other channels.