Permaculture is an integrated design system for sustainability. The word "permaculture" is a contraction of "permanent agriculture" or "permanent culture." Its roots are in the design of productive ecosystems for farms and gardens. A central theme in permaculture is the design of ecological landscapes that produce food. Emphasis is placed on multi-use plants, cultural practices such as sheet mulching and trellising, and the integration of animals to recycle nutrients and graze weeds. Permaculture concepts also reach beyond farming and gardens that into designs for all types of resilient, sustainable structures, both physical and social. It is a philosophy of maximum effort at the design stage to allow minimum effort and side-effects once the system is running, instead of the conventional method which is often the reverse.