Facebook was founded in 2004 by Mark Zuckerberg and fellow Harvard students. It grew rapidly, attracting over 100 million US users by 2011. In 2012, Facebook filed for an initial public offering and began trading stock on the NASDAQ. All social networking sites allow users to create profiles, connect with friends and view friends' connections. Additionally, features like status updates, profile pages, and friend lists are common across sites. Facebook integrates with other social platforms like Words with Friends, Twitter, YouTube, and Pinterest by allowing their use on Facebook profiles and pages.