This chapter provides an overview of some of the key issues associated with the management of customer relationships. It explores some of the implications of developments in mobile and digital technologies for the way in which existing customer relationships are managed. The chapter details the nature of the underpinning data that facilitates effective customer-relationship management (CRM) and highlights the need to carefully integrate online and offline CRM. This customer relationship memory differs from ordinary databases in that it is the memory of a specific customer relationship. The use of electronic customer-relationship management (eCRM) tools greatly helps an organisation's ability to collate customer information, such as personal and profile data, transactional data and communications data. Innovation in telecommunications, database management, and the World Wide Web has had a dramatic impact upon customer management. The notion of lifetime customer value is central to the concept of retaining and developing customer relationships.