The best command-line editor has just turned 20. Sorry, Emacs users; it's true.
It's the modal editor that scares many a command-line newbie, but its loyal following shows that once you break through the learning barrier, you cannot go back.
The old favourite started life on the Amiga as a Vi clone; in fact, Vim originally stood for "Vi iMitation" not the "Vi iMproved" that we know now. November 2, 1991 saw the first public release, and it took off from there.
For the full history of Vim, there is always Wikipedia, or read this history by Vim's creator Bram Moolenaar.
I could go on and on about why I prefer Vim to Emacs and Nano editors, but it is best summed up in this stackexchange answer.
"Your problem with Vim is that you don't grok vi" is very much a truism; once you realise that Vim's commands are actually a language, the whole process seems to fall into place.
There was that one time that I switched to a Dvorak keyboard for a few years, and lost all productivity in it for a long time indeed.
For those too new to the field to remember, try Vi for a while and see what you miss, then use ed and see how you survive. Programmers in the past worked with ed everyday, crazy trailblazers that they were.
Vim also helps out the real world; without Vim, I'm not sure I would have the same knowledge of the plight of Ugandan children. Vim is charity ware, and uses its own licence, not the GPL.
So, many happy returns to the editor where the colon key gets a bashing.