Relationship Marketing, through Customer Relationship Management (CRM) applications, is a practice guided by marketing philosophy and strategies. It is applicable through technological support, and is at the threshold of the areas of Administration and Information Technology. In order to better understand the attributes required for the effectiveness of these practices, with a greater organisational scope, and greater capacity for information on customer behaviour, it is necessary to understand that CRM is not limited to technological support, but constitutes a business philosophy and lasting relationships with customers. This book presents in a simplified way the foundations on which CRM is based.