The Psion Series 3 is a line of personal digital assistants (PDAs) released in the early 1990s by Psion, a British software and hardware company. Known for its compact design, the Series 3 featured a clamshell form factor, a full QWERTY keyboard, and a monochrome LCD screen. It ran the EPOC operating system, which allowed users to run various applications, including word processing and spreadsheets. The Series 3 was notable for its long battery life and robust software capabilities, making it popular among business professionals and tech enthusiasts. It came in several models, including the Series 3a and Series 3c, each offering improvements in memory and functionality. The device played a significant role in the evolution of handheld computing.