What makes a product sustainable/unsustainable ?

In order for a product to be sustainable, it should fall into one of the 5 R's, meaning the product can be:

- Recycled

- Re-used

- Re-fused

- Reduced

- Repurposed

After the product has served its intended purpose. 

Another thing which makes a product sustainable is what the product is made from. If the product is formed of materials from finite sources, then the product is unsustainable. A finite source is material which will eventually run out one day. For example: crude oil, which makes plastics, is a finite source, as the Earth only has a limited supply/reserve of crude oil. 

Lastly the carbon footprint of the product can increase/ decrease it's sustainability. If the product is made from materials sourced from all over the world, vast quantities of energy are needed to transport those materials to the factories, in turn making the product less sustainable. Also if the factory which makes the product wastes energy/ materials, that can also effect how sustainable a product is.