All of the clones provide additional features that make simple text editing easier and more powerful:
The ability to edit ex mode commands as you type them, possibly including a saved history of ex commands. Also, the ability to complete filenames and possibly other things, such as commands and options.
The ability to edit lines of essentially arbitrary length. Also, the ability to edit files containing any 8-bit character.
The ability to successively undo all of the changes you’ve made to a file.
The ability to search for text while you are typing the search pattern.
The ability to let long lines trail off the edge of the screen instead of wrapping.
The ability to select arbitrary contiguous chunks of texts upon which some operation will be done.
A visible indication of insert mode versus command mode, as well as indicators of the current line and column.
Users of the csh, tcsh, ksh, zsh, and bash shells have known for years that being able to recall previous commands, edit them slightly, and resubmit them makes them more productive.
This is no less true for editor users than it is for shell users; unfortunately, Unix vi does not have any facility to save and recall ex commands.
This lack is remedied in each of the clones. Although each one provides a different way of saving and recalling the command history, ...