Front end stuff...

A forward or preface should be written as a personal expression. It's your opportunity to explain why you wrote the book and what you hope readers will get out of it.

A prologue deals with elements you feel the reader should know but are not contained in the book. Think of the prologue in the first Star Wars adventure."In a galaxy..."

For example, if you were writing a nove about the betrothal of Mary and Joseph, you might include a prologue describing Palestine at that time.

If on the other hand if you wrote a non-fiction book on the relationship of Mary and Joseph as it pertained to Jewish tradition at that time, then you would write a forward.

Good Luck,

Here's Wikipedia's take on the difference between a preface and a foreword:

A preface is an introduction to a book written by the author of the book. An introductory essay written by a different person is a forewordand precedes an author's preface. The preface often closes with acknowledgements of those who assisted in the project. A preface is usually signed (and the date and place of writing often follow the typeset signature); a foreword by another person is always signed.

Click to expand...

In the bio for a non-fiction book, you might want to stress your credentials as they pertain to the topic--for instance, if you have a degree in religious studies, you'd highlight that.

But your agent and publisher should be able to help guide you on these. A preface or foreward isn't always necessary (but acknowledgments are always a good idea).