What is vi?

"vi" is an editor that has been a standard utility on just about every version of Unix since Unix systems had keyboards and display terminals. The fact that this site is "vi powered" means that it was created "by hand" using HTML, not using some software package that attempts to make things easy by obscuring what you're doing.

HTML is easy to use, and there are many tutorials on the web. A good reference site is the idocs Guide to HTML.