Exploring Requirements: Quality Before Design. Donald Gause and Gerald Weinberg
This book has been around for quite a while, but continues to be one of the important books in the field. Gause and Weinberg explore the area of requirements that most people find hard - the ambiguities, the difficulties in understanding people, the little things that are said that cause the requirements person to completely misunderstand the user's intention. It is not hard, say G & W, to get what you ask for. The problem is asking for what you really want. And this is the crux of the book - how to think about requirements, how to understand what the user is saying, how to listen to what is really being said.
It is not just the content that causes this book to remain popular. Don and Jerry's style has a lot to do with that. They are witty and wise. They entertain you as you learn. The stories of the requirements for the Do Not Disturb and the Superchalk products are particularly engrossing. They make sure that you are provoked as you work through their other examples.
But I feel that the lasting legacy of this book is the authors' ability to discuss frankly how requirements gathering is not an easy task. It is a challenge for the analysts and their users, indeed for all the stakeholders. G & W also talk about the delight when the requirements analysts understand what the user is thinking, even when the user is not articulating his thoughts.
This book is essential reading for everybody in the field of requirements.