Definition:
Typically found as part of the front matter of a book, in the acknowledgment the author acknowledges the contributions of organizations and individuals who he or she feels helped with the book. Editors, people or groups who provided research materials, actual persons who are mentioned in the book, and anyone else the author feels contributed to getting the book published are often mentioned in the acknowledgment.
Usually written by the author, in the case of some collections of writings by multiple authors, reprints long after the death of the original author, and other types of books there could be an acknowledgment penned by the editor(s) or publisher or other person involved in getting the book published.
Common Misspellings: acknowledgement
