Amazon Prime memberships grew by over 50 percent in 2015

Prime's Video and Audio content is getting more popular, particularly outside the US.

Amazon just announced its financial results for Q4 of 2015, and one of the big trends the company highlighted was the continuing strength of Amazon Prime, a service that has its roots in free two-day shipping but is now becoming a catch all for host of free media the company gives to subscribers. Amidst the many highlights the company is calling out are some notes on pretty major Prime growth: Amazon says that worldwide Prime memberships increased 51 percent in 2015 compared to the year before. Growth in the US came in at 47 percent, which means things picked up every faster internationally.

That strong international growth was mirrored in how customers are using Prime. Specifically, Prime Video streaming outside the US nearly doubled in Q4 2015 compared to a year ago. Even the fledgling Prime Music service (which still offers "only" 1 million songs, compared to the 35+ million that you'll get with Spotify, Apple Music and most of their competitors) is starting to grow. Amazon said that streaming hours in Q4 2015 more than tripled compared to a year ago. The service also went live in Germany and Japan in the quarter.

The improvements in Amazon's music service are notable given the rumors swirling around the company's intentions to built a full-fledged Spotify competitor. As usual, we have no idea how many people are actually using Prime Music -- and that explosive growth Amazon is citing likely has a lot to do with the fact that not a lot of people were using the service a year ago. Either way, it looks like Amazon's media ambitions extend beyond just its massive bookstore and the original TV shows it's making to round out Prime Video.

From a pure numbers perspective, Amazon had a strong holiday quarter. The company pulled in $35.7 billion in revenue in Q4, up 22 percent over a year ago. Profits saw an even bigger bump: $482 million in net income marked a whopping 125 percent increase over Q4 of 2014. The big holiday quarter helped Amazon to a profitable 2015, with total net income totaling $596 million on the year, compared to 2014's net loss of $241 million.

Amazon will be holding its quarterly financial call at 5PM ET, and we'll be listening in to see if the company has any more details on Prime, delivering packages by drones or anything else that may be of interest. We'll keep this post updated, so stay tuned.