The Brundtland Kommission published the concept of sustainable development for the first time in 1987. In this publication the term "sustainability" was defined as development "which responds to the needs of today’s generations without endangering the opportunities/possibilities of future generations". This means that today’s consumption of resources needs to be reduced in order to enable future generations to satisfy their needs as well.
Sustainability is built on three "pillars": environmental, economic and social dimensions. In order to manage sustainably all three dimensions need to be taken into consideration, not only economic success shall be pursued.
(Source: Lexikon der Nachhaltigkeit, www.nachhaltigkeit.info