消费，有时俗称花钱、买东西等，是人类社会特有，指人类通过货币购买有形或无形商品或服务，并从中得到个人欲望满足。人类消费活动或许是心血来潮（例如人们路过餐厅，挑起食欲），也可能对某些消费习以为常（例如一些家庭每天都买报纸），然而消费或者购买牵涉到非常复杂的决策过程，消费者根据他的收入、个人喜好、社会习俗、甚至身边朋友、家人购买行为对消费者本人产生影响。有些消费本身也是带有“不可避免”性质的，例如购买食物解决温饱问题；有些消费则具有可选性，例如购买金银首饰和私人汽车。如果被购买的是昂贵货品，还会驱使消费者作出货品和替代品之间的比较，才会出现消费的行为。

Consumption is a major concept in economics and is also studied by many other social sciences. Economists are particularly interested in the relationship between consumption and income, as modeled with the consumption function.

Different schools of economists define production and consumption differently. According to mainstream economists, only the final purchase of goods and services by individuals constitutes consumption, while other types of expenditure — in particular, fixed investment, intermediate consumption, and government spending — are placed in separate categories (See consumer choice). Other economists define consumption much more broadly, as the aggregate of all economic activity that does not entail the design, production and marketing of goods and services (e.g. the selection, adoption, use, disposal and recycling of goods and services).