Sustainable development means building or doing things in a way that doesn't use up all the natural resources of the earth. This way, we can use the same resources again and again, and they won't run out. Using up all of the earth's resources means that no one will be able to use them ever again. Sustainable development also means we have to be careful with how much waste we make, so that we don't pollute our environment and harm animals and plants. A great example of sustainable development is using reusable bags at the store instead of plastic ones. This way, fewer plastic bags need to be made, which saves resources and helps the environment.