Facebook is about to get filtered.

The social network announced Monday that it is buying photo-sharing service Instagram, a two year-old San Francisco-based company that has attracted more than 30 million users, for $1 billion in a cash and stock deal.

The deal marks an attempt by Facebook to maintain dominance in an area that has proved one of its stickiest and most popular features: photo sharing. At the end of last year, Facebook users were uploading more than 250 million photos a day, on average, according to Facebook's filing with the SEC. The social network's members also spend nearly a fifth of their time on the site browsing photos, a 2011 comScore study found.

Instagram has, in just two short years, developed an offering that has proved attractive and compelling to a diverse group of users, and Facebook no doubt hopes to capitalize on the photo sharing app's expertise, particularly in mobile.

In an update posted on his Facebook profile, Facebook co-founder and CEO Mark Zuckerberg explained that the "talented team" at Instagram will be joining Facebook to help the social network add new features to its photo-sharing offerings.

"For years, we've focused on building the best experience for sharing photos with your friends and family," the Facebook CEO explained. "Now, we'll be able to work even more closely with the Instagram team to also offer the best experiences for sharing beautiful mobile photos with people based on your interests."

Zuckerberg also wrote, "We will try to learn from Instagram's experience to build similar features into our other products. At the same time, we will try to help Instagram continue to grow by using Facebook's strong engineering team and infrastructure."

Zuckerberg noted Facebook is "committed to building and growing Instagram independently," a sentiment Instagram CEO Kevin Systrom echoed in his own post about the deal.

For example, Instagram users will continue to have the ability to share photos to other social networking sites besides Facebook (and also abstain from sharing Instagram photos with Facebook), and will be able to keep their Instagram follower lists distinct from their Facebook friend groups, Zuckerberg wrote.

Zuckerberg noted that the deal is an exceptional one for Facebook given the size of Instagram's userbase.

"This is an important milestone for Facebook because it's the first time we've ever acquired a product and company with so many users," Zuckerberg wrote. "We don't plan on doing many more of these, if any at all. But providing the best photo sharing experience is one reason why so many people love Facebook and we knew it would be worth bringing these two companies together."

Instagram, which was founded in 2010, has 13 employees. Systrom wrote in a blog post that the company's employees are "psyched" to be joining Facebook.

"It’s important to be clear that Instagram is not going away," he said. "We’ll be working with Facebook to evolve Instagram and build the network. We’ll continue to add new features to the product and find new ways to create a better mobile photos experience."

Many Instagram users are less "psyched" about the deal. See how people are reacting to the news in the slideshow below.