KEY POINTS
An Amazon Robotics robot moves a rack of merchandise at an Amazon fulfillment center on January 20, 2015 in Tracy, California.

Amazon is quietly expanding Prime Now, its free 2-hour delivery service. After originally launching in one zip code in New York City back in 2014, it's now available in more than 45 cities in eight countries. This year alone, it's added 14 more cities.

But don't feel bad if you haven't heard about it yet. Amazon may be keeping it under wraps as it ramps up its offerings and perfects its fastest delivery method yet.