(1) A basic definition says that sustainability means meeting today’s needs without harming future needs. (2) That definition is useful, but it can create a misconception: readers may think sustainability refers only to environmental protection. (3) To refine the idea, the author adds that it can also involve economic durability and community well-being. (4) The added detail helps readers understand that the idea includes several connected kinds of long-term planning. (5) The paragraph therefore moves from a simple definition to a more careful one.