There Is an Older Editor Inside Vim

Before screens, editors answered one line at a time

You save with :w and leave with :q. Ever wondered why it is a colon? The moment you press :, you are talking to a different editor living inside Vim.

In the 1970s a terminal with a screen was still a luxury. Editors of the day worked a line at a time. Bill Joy, then a student at Berkeley, wrote one of them, ex, and added a mode that let you edit while watching a screen, and he called that mode vi, short for visual. So vi was never a separate program from ex, and on many systems the two names still point at the same binary. Vim is their descendant. That is why pressing : hands you back to the ex side, and why Vim's own help still calls anything starting with : an Ex command.

Every time you type :wq, a fifty-year-old editor answers one more line.