This article provides an in-depth explanation of the history and functionality of terminals in UNIX systems. It explains the different modes of terminal input, including canonical and noncanonical, and how they are represented by files in the /dev/ directory. The use of the tty command to determine the current terminal file in use is also covered. Additionally, the author dives into the concept of pseudoterminals, or /dev/pts, which are a feature in the Linux kernel that allows remote terminal access and the creation of terminal emulators. The article explains the two parts of a pseudoterminal, a ptmx and a pts, and how they are used to emulate user input and read program output. Overall, this article is an educational resource that provides a thoughtful approach to understanding terminals and pseudoterminals and their role in modern systems.