What just happened? Remember when Netflix was a disc-by-mail service only? It might surprise you to learn that the DVD-rental part of its business is still going, and it’s just passed a significant milestone: shipping the five-billionth disc.

It was 21 years ago when Netflix began delivering DVDs to customers, reaching its first billion back in 2007. As reported by Variety, the company’s video streaming service launched soon after as an added bonus for subscribers, long before it became the global phenomenon we know today.

It took another four years before Netflix split its DVD-rental and streaming subscription services into two separate plans and businesses. Unsurprisingly, the number of subscribers to the former has dropped significantly over the years, from 14 million in 2011 to 2.4 million in the second quarter of this year. The company has also reduced the number of DVD distribution hubs in the US from its peak of 50 to just 17 as of last year.

You might wonder why Netflix hasn’t pulled the plug on its disc service, especially when its subscriber figures pale in comparison to the company’s 151 streaming subscribers. It’s because DVDs are still profitable, contributing almost $46 million to the firm’s profits in Q2 of this year. While that’s not a huge amount compared to Netflix as a whole, it’s still enough to justify keeping the service around.

For those interested, the five-billionth disc shipped was the Elton John biopic Rocketman, which isn’t available to stream on Netflix.