What makes Ebay and Amazon successful?
All successful online businesses started from the scratch. This include the immense research. That has been conducted to fully understand the market of the internet and see how they would fit into the niche. If you are aware, almost any product searches on popular search engine such as Google would display the first result by Ebay or most likely Amazon. These results will show them specific product name that are available in the sites. Hence we call them as authority sites.
Authority Website
An authority website is one that holds vast pages, products and keywords. On the other hand, a sniper site  focuses only on a single product. In addition to their massive products, keywords and pages, they will also be receiving abundance of backlink from other sites. But being authority site is not the sole reason. Other characteristics include having most of their pages indexed onto the keywords people are looking for and the efficiency of their websites as e-commerce.
Good System
Any e-commerce site must have a good system (to sell); It is as simple as that. But a good system includes having user-friendly interface that allows people to browse around comfortably and the navigation must be smooth. Everything they do in your website must be able to facilitate their journey to a pleasurable buying experience. So by having a good shopping card and all other elements required to enhance their buying experience would be favorable.
Check-out Experience
Their check-out experience is probably the most important part of the process. When the visitors are on the last stage to pay for their products. As authority sites like Amazon and Ebay are known for having enough credibility, you will need to ensure your site convey credibility.  The reason is; potential buyers would not have that last minute resistance. As a seller, you should leverage payment method systems to increase your credibility. PayPal for instance is one of the most preferred payment option for online users. Using such reliable payment gateway option would boost the confidence of most buyers. Last thing in mind is that you must ensure your site to be online for 365 day. You rarely see any downtime coming from Ebay or Amazon, so choosing a reliable web hosting would also contribute to the success of your e-commerce.