To shape our world, humans have always used tools. Today, the range of possibilities is vast, from screwdrivers to tractors to the world wide web. But how do you know what tools and technologies are the right ones for the task you wish to undertake? How can you select the ones which will deliver the greatest benefit for the least cost and labour? And how can you ensure you choose tools and techs which avoid environmental damage? This section will help you answer all these questions.