Mapping and, ultimately, deciphering the human genome is a major human and scientific adventure that involves thousands of researchers world-wide and considerable funds. Bertrand Jordan, an active scientist in this field, became also a privileged observer through a sabbatical year devoted to visiting nearly a hundred participating laboratories around the world. This placed him in an ideal position to see, discuss, record and analyse progress and difficulties in this endeavour. These observations are the basis for a regular feature, "Chroniques Genomiques" (Tales of the Genome) published in the French periodical médecine/sciences. This book is an integrated, expanded and updated version of the 1990-1993 chronicles. It provides a technically detailed but accessible account of the "Genome World" from the viewpoint of a practising scientist. It describes the strategies implemented in settings that range from small laboratories to semi-industrial installations such as "Généthon", and the associated questions in terms of national policies, economic stakes and ethical issues.