Aggregate supply 

Aggregate supply is the total amount of goods and services (real GDP) that firms are willing and able to supply at a given time at a particular time period.

Positive relationship between the output that firms are willing and able to provide and the selling price of goods and services in the economy.

Short run aggregate supply- shows the total planned national output at different price levels.

A rightward shift in SRAS means that firms produce a larger quantity of real GDP at any price level, or short-run aggregate supply increases. A leftward shift in SRAS means that firms produce a smaller quantity of real GDP at any price level, or a decrease in short-run aggregate supply.

Costs of production are the costs that firms faced during a production proces. Examples of the variables that affect the costs of factors of production include labour costs, costs of raw materials, exchange rate, interest rates, indirect taxes and bureaucracy and administration. That factors will shift the SRAS curve.

Non-price factors shift the curve to the left or right and change in price cause the movement alon the curve.

When national output expands and economy increase their productive capacity the SRAS become more price inelastic.

Long run aggregate supply