I recently read a book that began with a Forward. I don’t know who edited the book, but I suspect the writer intended the page to be a foreword, which is a noun that means preface. Forward is an adverb meaning onward or advancing.
The same mistake could happen with afterward and afterword. An afterword appears at the end of a book and is, as its name suggests, a postscript by the author. Afterward is an adverb meaning later.
When in doubt, consult a dictionary.