The phrase "throwaway culture" is a phrase that attempts to describe the habits that as a society we have towards manufactured products and resources. The idea of a "throwaway culture" is that we engage in consumerism excessively. We take pleasure in new things, and when something does not work anymore, we tend to throw it away, as opposed to fixing it. Even worse, we might throw things away even when they do work, simply because we do not consider it trendy or because we want to buy new things now.
