Agricultural extension is an important tool for rural development, especially in less industrialized counties - extension workers play a vital role in educating farmers to produce better crops and more productive animals at lower cost. The new edition continues to present basic principles which can be applied to all situations, but has been revised to take account of the changes that have occurred during the last eight years. Major developments since the first edition was published in 1988 include: Increasing farm yield is no longer the only goal. Environmental conversation through sustainable farming practices is now an essential part of extension work following the 1992 Earth Summit which put sustainable development on the international political agenda, Participatory approaches ("empowerment") are now emphasised, Increased role of non-government organizations in extension work; Availability of information technology in developing countries, Increasing stress on competition and the role of private enterprise