Aggregate demand implies the total demand of final goods and services by all the people in an economy. Aggregate demand is the summation of consumption expenditure (C), investment expenditure (I), government expenditure (G), and net earnings from foreign transactions (X - M) (Where, X is exports and M is imports).
Algebraically,
AD = C + I + G + (X – M)
i. Consumption expenditure (C): Consumption expenditure refers to the total expenditure incurred by all the households in an economy on different types of final goods and services in order to satisfy their wants. Consumption expenditure can be further divided in two categories as - Autonomous consumption expenditure and Induced consumption expenditure. Autonomous consumption expenditure is independent of the levels of disposable income whereas, induced consumption expenditure varies directly with the level of disposable income.
ii. Investment expenditure (I): Private investment expenditure refers to the planned (ex-ante) total expenditure incurred by all the private investors on creation of capital goods such as expenditure incurred on new machinery, tools, buildings, raw materials etc. Broadly, investment can be categorised into two types- Autonomous investment expenditure and Induced investment expenditure. The autonomous investment expenditure is independent of the rates of interest and levels of income whereas, the induced investment expenditure varies inversely with the rate of interest and directly with the levels of income.
iii. Government expenditure (G): Government expenditure refers to the total planned expenditure incurred by the government on consumption and investment purposes to enhance the welfare of the society and to achieve higher economic growth rates. The government expenditure comprises of both investment expenditure as well as consumption expenditure.
iv. Net exports (X – M): Net exports of a country refers to the difference between the demand for domestically produced goods and services by the rest of the world (exports) and the demand for goods and services produced abroad by the residents of that country.