Social media refers to online platforms that allow users to connect, share content, and interact. Popular social media tools include Facebook, Twitter, Instagram, YouTube, and Whatsapp. Founders of these major sites include Mark Zuckerberg of Facebook, Evan Williams and Jack Dorsey of Twitter, and Jan Koum and Brian Acton of Whatsapp. In 2016, Facebook had over 1.6 billion users, YouTube had 1 billion, and Instagram and LinkedIn each had over 400 million users. While social media allows for connection and information sharing, overuse can be distracting and lead to addiction, and excessive social media use has been linked to some psychological issues in teenagers.