What is a BRD, Why Do I Need It, and What Goes in It?

This book includes the following:
Defining the Approach for Eliciting Requirements
Obtaining Detailed Requirements
Prioritizing Requirements
Documenting Requirements and Attributes of Requirements
Real examples of vague vs. detailed requirements
Three Requirements Eliciting Techniques
What is a Business Requirements Document(BRD)
Sections of the BRD and what goes in those sections