Definition: an authority book
An authority book is a nonfiction book written by an expert to show what they know, earn trust with the people they want to serve, and create opportunities such as speaking, media interviews, and client conversations. Big Impact Books calls it an authority engine because it keeps working long after launch.
It is different from a book written mainly for retail sales. Success is measured in doors opened, not only copies sold. That matters because, according to BookScan figures cited by Berrett-Koehler, only 33.9 percent of the titles in that sample sold more than 1,000 copies in their first year.