
Amazon is a multinational technology company focusing in e-commerce, cloud computing, and artificial intelligence in Seattle, Washington.
It is one of the Big Four or “Four Horsemen” of technology along with Google, Apple and Facebook due to its market capitalisation, disruptive innovation, brand equity and hyper-competitive application process.

Fulfilled by Amazon
The reason most people don’t realise that Amazon is a marketplace like eBay is it generally smooths over all the roughs and bumps. Sellers have two options:
They can list their products on Amazon and, when an order comes through, pack and ship it themselves.
They can list their products on Amazon and bulk ship any number of items to an Amazon warehouse. When an order comes through, Amazon workers pack and ship it like it’s an Amazon product. This is Fulfilled by Amazon.

For sellers, the big advantage of Fulfilled by Amazon is Amazon handles everything. They don’t need to run their own store, handle payment processing, deal with a shipper, pack things up, or customer care—for a small fee, Amazon does it. Sellers sometimes refer to Fulfillment by Amazon as “FBA.”
For customers, the advantage is that they get the same, regular Amazon experience, including stuff like Prime, free shipping, and the like, for an extra 338 million products that Amazon doesn’t sell directly. Most people—including me—don’t even notice when they’re not buying directly from Amazon. The packages arrive at your door just the same.
Source: How-To Geek