Social media refers to websites and applications that allow users to share content and communicate. Facebook has the most users worldwide, with over 1.5 billion. Social media is widely used, with over half of the global population being active on mobile social platforms. It is used for various purposes like staying connected with others, sharing ideas and reviews, and raising awareness for causes. While it has benefits like education and connectivity, it also has some negative effects like addiction, privacy issues, and cyberbullying.