An Ebook is a book that exists in electronic form rather than printed on paper.
Ebooks can be read on a computer.
You can download many chess Ebooks for free from the Internet!
These are mostly older chessbooks, now out of copyright, which means that they can be copied and distributed without paying royalties to the author.
Project Gutenberg is one of the best sources of free EBooks as it is entirely devoted to converting out of copyright books to electronic form such that they are available to everyone for free.
The following are a very small sample of the types of books that you can download for free from Project Gutenberg:
For a greater selection, visit the Project Gutenberg.