This book presents product development and systems engineering practices, activities, and artifacts from the perspective of needs and requirements as they are defined, implemented, and managed across the system lifecycle. Comprised of 16 chapters, Needs and Requirements Manual displays a keen focus to the lifecycle perspective and provides practical guidance on activities required to successfully complete system development, system verification and validation, the needs and requirements of the system as well as the system verification and validation artifacts. By supporting the parent handbook published by Wiley, INCOSE Systems Engineering Handbook, this book includes a detailed guidance and lessons learned from hundreds of years of experience of the authors, contributors, and reviewers, offering a unique collection of relevant information. Having received a strong acceptance and support from the SE community, this manual will fill a gap in the SE market and provides the reader with the detail to successfully implement the INCOSE SE Handbook processes and activities.