Definition - What does Vi mean?
Vi is a screen editor for Linux, Unix and other Unix-like operating systems. Pronounced (vee-aye), vi stands for visual instrument. It is a widely-used default text editor for Unix-based systems and is shipped with vitually all versions of Unix. It exclusively uses the keyboard and provides a very efficient interface for editing programs and scripts.
Vi is somewhat difficult to learn, but programmers are happy to go through the learning curve to gain the provided efficiency. In comparison to a general purpose word processor program, VI is tailored to a more specific profile of usage and users – programmers of UNIX-based systems.
This term is also known as visual editor and VI.
Techopedia explains Vi
Unlike the widely popular Windows-based word processors (such as Microsoft's Notepad and Word), VI does not provide any formatting or “What You See Is What You Get” capabilities.
The original VI program was written by Bill Joy in 1976 and become part of the Single Unix Specification Standard, demanding every conforming Unix distribution to include it. Until the rise of Emacs in 1984, another popular text editor, VI was the de facto standard Unix editor. Even 2009 survey of Linux Journal readers have awarded VI as the highest used text editor leaving Emacs to second place.
Vi actually has an underlying editor known as ex. That is, vi is the visual mode of ex. To execute commands inherent to the ex line editor, the colon (:) is used. There are also two main modes of operation: the command mode and the insert mode. To return to the command mode, simply press the ESC key.