The current state of the economy consumes many fossil resources (i.e. they are not infinite) and generates a lot of waste, which can only be converted back into usable materials by using large amounts of energy. This contributes to both the exhaustion of finite resources and the climate crisis.
In nature, everything is part of a cycle. What dies, does not remain as waste, but serves as food or it decomposes and releases nutrients into the soil. This serves as a model for the circular economy: The supply and trade chain should be regenerative and global, getting by without finite resources. The benefit of all products and materials should always be as high as possible in order to repair, process, or reuse them. There is no waste or reuse in the closed-loop supply chain. Existing resources are always reused. The implementation can roughly be summarised under the three R-strategy: Reduce, Reuse, and Recycling.
How “recyclable” a product is can be indicated by the Material Circularity Indicator (MCI). The prerequisite for this is a completed Life Cycle Assessment (LCA), which covers all emissions from resource extraction, through production, to use and end-of-life treatment.