Instagram is a photo and video-sharing social networking service owned by Facebook, Inc. It was created by Kevin Systrom and Mike Krieger, and launched in October 2010 exclusively on iOS. A version for Android devices was released a year and half later, in April 2012, followed by a feature-limited website interface in November 2012, and apps for Windows 10 Mobile and Windows 10 in April 2016 and October 2016 respectively.
The service originally only allowed content to be framed in a square (1:1) aspect ratio, but these restrictions were eased in 2015. The service added messaging features, the ability to include multiple images or videos in a single post, and "Stories" — similar to its main competitor Snapchat — which allows users to post photos and videos to a sequential feed. As of January 2019, the Stories feature is being used by 500 million users daily.
After its launch in 2010, Instagram rapidly gained popularity, with one million registered users in two months, 10 million in a year, and 1 billion as of May 2019. In April 2012, Facebook acquired the service for approximately $1 billion in cash and stock and as of October 2015, over 40 billion photos had been uploaded to the service. Early investors include Greylock Partners, Thrive Capital, Baseline Ventures, Benchmark, Sequoia Capital, Lowercase Capital, and Andreessen Horowitz.