To feed the present human population, farmers use the land and add to it their labour, their animals, buildings, tools and machinery, a variety of products bought in from other industries—from fertilisers and pesticides to computers and mobile phones—and professional services from vets, advisers, and scientists. ‘Inputs into agriculture’ considers these inputs in turn. Different kinds of farms demand different kinds of inputs. Farmers will also use tradition, experience, and knowledge to help them cultivate the land and care for their animals. Combining information on different farming outputs and inputs shows how a wide range of farming systems can be produced.