Pinterest is a social media platform where users can create boards to organize and share images they find online. Users can upload or "pin" images to their customized boards on specific topics. The platform has grown rapidly since its launch in 2010, reaching over 4.5 million users in just 6 months in 2011. Key features of Pinterest include pinning images, organizing them into boards, following other users, repinning images from others to your own boards, and sharing pins across social networks like Facebook and Twitter.