Probably the easiest way to describe an introduction to permaculture is to share what Wikipedia said:
Permaculture is a system of agricultural and social design principles centered around simulating or directly utilizing the patterns and features observed in natural ecosystems. The term permaculture was developed and coined by David Holmgren, then a graduate student, and his professor, Bill Mollison, in 1978. The word permaculture originally referred to “permanent agriculture”, but was expanded to stand also for “permanent culture”, as it was understood that social aspects were integral to a truly sustainable system as inspired by Masanobu Fukuoka’s natural farming philosophy.
It has many branches that include, but are not limited to, ecological design, ecological engineering, environmental design, and construction. Permaculture also includes integrated water resources management that develops sustainable architecture, and regenerative and self-maintained habitat and agricultural systems modeled from natural ecosystems.
Mollison has said: “Permaculture is a philosophy of working with, rather than against nature; of protracted and thoughtful observation rather than protracted and thoughtless labor; and of looking at plants and animals in all their functions, rather than treating any area as a single product system.”
I am a believer in the idea of permiculture, of working with things as they want to be rather than forcing them to adapt – it makes gardening easier when you work with nature. I once did a podcast with Paul Wheaton, one of the leading figures in the American permaculture movement and the owner of the permies.com forum.