Pioneering content discovery engine StumbleUpon is calling it quits after more than 16 years of service. Over its lifetime, the service fed nearly 60 billion websites to more than 40 million users according to co-founder Garrett Camp.

StumbleUpon launched in 2001 while Camp was still in graduate school at the University of Calgary as one of the web's first content discovery / recommendation platforms. Search engines and web portals like AOL existed back then but traditional social networks such as Facebook and social news aggregators like Reddit did not, making it somewhat of a challenge to come across new content with ease.

StumbleUpon solved that issue by serving up fun and interesting content at the click of a button. It was easy to use and more often than not, delivered on its promise with engaging content.

As content creators can attest to, if you were lucky enough to get your site into StumbleUpon's rotation, it was a surefire way to generate loads of traffic that was comparable to getting featured on Slashdot, Digg or Reddit.

Unfortunately, what made StumbleUpon so great - its simplicity - also contributed to its decline.

Since StumbleUpon's start, the number of people with Internet access has grown nearly tenfold. Mobile phones and social media have changed the landscape of the Internet and our daily lives. Detailed data is big business. In short, simply clicking "I like it" on a website or article of interest is no longer enough. Contextual curation is key and that's something SU lacked.

Over the coming months, StumbleUpon accounts will be transitioned into, a service that has been described as something like Pinterest for content. StumbleUpon will officially shut down shop on June 30.

As for Camp, he'll be just fine either way. If you recall, he co-founded Uber back in 2009 and currently ranks among the world's wealthiest individuals with a net worth of $4.8 billion according to Forbes.