Files in /dev are special devices files that help Linux operate as intended. There are a few major devices types: block, character, and special character devices.
Block devices
These devices are used for processing data that is stored in blocks, such as hard drives, SSDs, USB flash drives, or other etc. These files are commonly seen in /dev/ with file names such as sda, sdb1.
Character devices
Character devices handle streams of data one character at a time. For example, keyboards, terminals, or serial ports are handled via this device type. An example of this file is /dev/tty, which is a terminal interface.
Special character devices
These are unique devices that don’t represent hardware, but instead function as utilities for the system. They include stuff like /dev/null, /dev/zero, and /dev/urandom.