About the book:

"A Byte of Vim" is a book which aims to help you to learn how to use the Vim editor (version
7), even if all you know is how to use the computer keyboard.
The first part of this book is meant for new users who want to understand what Vim is and learn how to use it.
The second part of this book is for people who already know how to use Vim and want to learn about features that make Vim so powerful, such as windows and tabs, personal information management, making it a programmer's editor, how to extend Vim with your own plugins, and more.

About Vim: (from Wikipedia)

Vim is a text editor originally released by Bram Moolenaar in 1991 for the Amiga computer[citation needed] (based on an earlier editor, Stevie, for the Atari ST, created by Tim Thompson, Tony Andrews and G.R. (Fred) Walter[original research?]). The name "Vim" is an acronym for "Vi IMproved"[2] because Vim is an extended version of the vi editor, with many additional features designed to be helpful in editing program source code. Originally, the acronym stood for "Vi IMitation", but that was changed with the release of Vim 2.0 in December 1993.[3] A later comment states that the reason for changing the name was that Vim's feature set surpassed that of vi.[4]