The waste hierarchy is a classification of waste management options in order of their environmental impact, such as: reduction, reuse, recycling and recovery. The waste hierarchy has five steps: prevention; preparing for re-use; recycling; other recovery, e.g. energy recovery; and disposal.

The waste hierarchy has taken many forms over the past decade, but the basic concept has remained the cornerstone of most waste minimisation strategies. The aim of the waste hierarchy is to extract the maximum practical benefits from products and to generate the minimum amount of waste.

Source reduction is typically measured by efficiencies and cutbacks in waste. Toxics use reduction is a more controversial approach to source reduction that targets and measures reductions in the upstream use of toxic materials. Toxics use reduction emphasizes the more preventive aspects of source reduction but, due to its emphasis on toxic chemical inputs, has been opposed more vigorously by chemical manufacturers.The 3 R 's represent the ' Waste Hierarchy ' which lists the best ways of managing waste from the most to the least desirable. Many of the things we currently throw away could be reused again with just a little thought and imagination.