A smartphone is a mobile phone that has more advanced computing capabilities and connectivity than a basic phone, allowing users to access the internet, apps, and make calls and messages at low cost. The document discusses the major mobile operating systems, popular smartphone models for Android, iOS, and Windows Phone, and how smartphones have improved people's lives by making many tasks easily accessible from their phones. It concludes by noting the ongoing evolution of smartphones and their potential to revolutionize communication in the coming years.