The Palm Treo is a line of smartphones that combines a mobile phone with personal digital assistant (PDA) features. Launched in the early 2000s, it was one of the first devices to integrate a full QWERTY keyboard, making it easier for users to send emails and text messages. The Treo ran on the Palm OS operating system, which was known for its user-friendly interface. Over the years, various models of the Treo were released, each improving on features like camera quality, battery life, and connectivity options. The device was popular among business professionals for its ability to manage contacts, calendars, and tasks efficiently. Ultimately, the rise of touchscreen smartphones led to the decline of the Treo's popularity.