Dropshipping is selling someone else's product, and having them send the product to the customer. This is best seen in affiliate offers, but can also be done on your own with a direct supplier willing to hold the product, and ship it to your customers as orders are processed.
Many people have been removed from Ebay for dropshipping, but Amazon seems to have leveraged this method to allow you to refer people to their products and they take care of the fulfillment for you for a fee.
Without consistent involvement, research, and large volume of sales, this is a difficult business model to scale and grow long term. (In my opinion...)