Instagram 7 things to know

In its largest-ever acquisition, Facebook will pay $1 billion in cash and stock for Instagram, a 2-year-old photo-sharing application developer. Facebook, which is expected to raise $5 billion via the largest Silicon Valley initial public offering by May, will acquire Instagram's entire team. Wondering Instagram -- the company Facebook is shelling out a billion for -- is all about? Read on to find out.

What is it
Instagram is a social network built around photography. Free to use, Instagram lets people add various effects to the photos they snap with their mobile devices and share them with friends. Some of these make the photos look as if they've been taken in the 1970s or on Polaroid cameras.

Compatiblity
Presently, users can share their photos on a photo-by-photo basis on Flickr, Facebook, and Twitter.

Privacy on Instagram
All photos are public by default which means they are visible to anyone using Instagram or on the instagr.am website. However, in case a user chooses to make his account private, then only people following him on Instagram will be able to see his photos.

Popularity charts
Instagram says that as of the end of 2011, its users had uploaded some 400 million photos or about 60 pix per second. The app launched on Android store recently. After a week in the Android store, Instagram is the top-ranked free app not made by Google and No. 3 overall, behind Google voice search and maps. Facebook is eighth.

Instagram holds the record for the fastest app to reach 1 million downloads. Apple named it the app of the year in 2011.

Employees
Instagram has roughly a dozen employees based in San Francisco. The company reportedly closed a $50 million funding round last week from investors including Sequoia Capital and Greylock Partners. The funding valued the company at $500 million.

Management team
Instagram CEO and founder is Kevin Systrom. A Stanford University graduate, Systorm has worked with was an intern at Odeo, the company that spawned Twitter. Systrom has also worked with Google for two years.

What happens to Instagram post Facebook buy
Facebook said it would continue to develop Instagram as an independent app that remains compatible with other social networking services.