The acquisition isn't just about saving articles either. A spokesperson said that the company will also integrate some of Instapaper's search technology into Pinterest too. Steve Davis, lead product manager in Pinterest, said in a statement: "As the world's catalog of ideas, we're focused on making it easy to save and discover content on any device. The Instapaper team are experts in saving, curating and analyzing articles, and they're a welcome addition ​to Pinterest. Instapaper will work with us to continue building indexing and recommendations technologies, and we look forward to building great products together."

In a lot of ways, the acquisition makes sense. It's a way for Pinterest to leverage a feature that not many people know about, plus it's now able to use Instapaper's tech to help the discoverability of its other pins too. Pinterest could now very well be positioned to be the one-stop shop for bookmarking anything and everything on the web. In fact, the company changed its "Pin It" button to "Save" a few months ago to signify just that. Other bookmarking sites like these exist too of course -- Delicious, Pocket and Newsvine spring to mind -- but few of them have Pinterest's clout.

"The missions of Instapaper and Pinterest are aligned in helping people easily save content," said Brian Donohue, Instapaper's CEO, in a statement. Similarly, he said Pinterest's tech will be useful to Instapaper too. "The Pinterest team is working on unique technical challenges, and their collective skill will add tremendous value to Instapaper."