How to fit an entire economy into one formula.
The expenditure approach adds four items: private consumption, business investment, government spending and net exports, meaning exports minus imports. GDP = C + I + G + (X − M). Imports are subtracted because they already sit inside consumption and investment but weren't produced at home. If the figure rises only through prices, that's nominal growth; real growth subtracts inflation.
Useful: When you hear "growth", ask: nominal or real? The difference is inflation.
Source: de.wikipedia.org