Self-sufficiency (also called self-containment) is the state of not requiring any aid, support, or interaction, for survival; it is therefore a type of personal or collective autonomy. On a national scale, a totally self-sufficient economy that does not trade with the outside world is called an autarky.The term self-sufficiency is usually applied to varieties of sustainable living in which nothing is consumed outside of what is produced by the self-sufficient individuals. Examples of attempts at self-sufficiency in North America include simple living, homesteading, off-the-grid, survivalism, DIY ethic and the back-to-the-land movement.Practices that enable or aid self-sufficiency include autonomous building, permaculture, sustainable agriculture, and renewable energy.The term is also applied to limited forms of self-sufficiency, for example growing one's own food or becoming economically independent of state subsidies.The entire human population of the world was, at one time, self-sufficient. Families and groups made their own clothing, tools, weapons, boats and huts. They used gathering, hunting, herding and farming to find/hunt/grow their own food. As the population of the world grew, the wild food supply dwindled. People began to specialise, and to rely on herding and farming more; relying less upon gathering and hunting. In modern times, many farmers produce food on specialised farms. A large part of the worlds population now depends on these farmers to make their food for them. Many in developed nations now depend on job salaries to buy food, clothes, and shelter, rather than making these things from raw materials found in the environment. There are still societies which continue to be self-sufficient, never having given up traditional ways of food gathering and food making. If these people have no jobs and make no salaries, then they are often listed as unemployed.[citation needed]