What is Investment in terms of economy?

All income expended by firms or government agencies on capital goods for use in their productive activities. Aggregate investment in a national economy is the total amount of spending in order to maintain or increase the stock of physical goods not intended for immediate consumption by the purchasing entity but rather for use in producing other kinds of goods or services to be delivered to others. Keynesians start with accounting definitions, where Savings = Investment, by construction, and tend to emphasize the nonproductive (zero sum) nature of all vehicles by which savings eventually ends up as capital. In a Keynesian sense, savings is whatever is left over after income is spent on consumption of goods and services, investment is what is spent on goods and services that are not 'consumed', but are durable. Since Income = Output, Savings = Investment for the total world's economy (or for a hypothetical 'closed' economy with zero foreign trade). Income = Consumption + Savings ? Output = Consumption + Investment ? Income = Output ? Consumption = Consumption ? Savings = Investment read less