On the consumer side, Amazon has an estimated 180 million Prime subscribers in the U.S. The $139 annual subscription includes speedy shipping as well as two-hour grocery delivery and digital services like Prime Video and Amazon Music.
Retailers that want to take advantage of Prime's massive customer base can pay a fee to add Buy with Prime to their site, and utilize Amazon's fulfillment network when purchases are made using the button. Amazon said in September that Buy with Prime orders through merchants' sites are up more than 45% this year from a year earlier.