iPhones are a line of smartphones designed and marketed by Apple Inc. Key features of iPhones include their multi-touch displays, iOS operating system, high-quality cameras, and strong security features like Touch ID and Face ID. Popular iPhone models include the affordable iPhone SE, the latest iPhone 12 with advanced technology, and the iPhone 11 and XR which offer great features at reasonable prices. iPhones provide benefits such as an intuitive interface, integration with Apple's ecosystem, regular software updates, and a premium build quality.