In an economic system, consumers are those parties who acquire
goods and/or services for
personal use (as opposed to
resale). They stand opposite
producers: those who create the goods and/or services. All producers are also consumers, but consumers do not necessarily have to be producers.
Under a system of market fascism, such as modern American neoliberal capitalism, all members of a society are expected to primarily be consumers. Their role as consumers supercedes any meaningful sociopolitical participation beyond acquiring material goods. Consumer desires are often excessively manipulated and molded by marketers in order to steer them toward useless, high-cost products with famous brand names.
Under a more just and fair economic system, such as Participatory Economics, or "Parecon", (as outlined by Michael Albert in his book Thinking Forward) consumers would be made aware of the "true social cost" of the products they consume, and use this information to form their consumption habits. True Social Cost considers such things as the environmental damage a product both creates and requires in manufacture, accurate labor costs, etc. In essence, True Social Cost reflects the "full effects on people and society", both positive and negative.
Consumption should, ideally, be balanced with Production and Allocation in such a way as to promote the most fair and just economy possible.