Vi is a text editor that is widely used in the Unix and Linux operating systems. It was created by Bill Joy in the late 1970s and is known for its efficiency and speed. Vi operates in different modes, primarily the command mode and insert mode, allowing users to navigate and edit text effectively. Vi is often favored by programmers and system administrators due to its powerful features and minimal resource usage. It can be accessed through the terminal, making it a versatile tool for editing configuration files and writing code. Many users appreciate its keyboard shortcuts, which can enhance productivity.