:the total supply of goods and services that firms in a national economy plan on selling during a specific time period. It is the total amount of goods and services that firms are willing to sell at a given price level in an economy.

Higher prices motivate profit-seeking firms to increase output. This is because of diminishing returns and thus rising marginal costs that arise because one or more of the inputs or factors of production does not change in the short run and is assumed to be fully employed at all times. Usually this is fixed capital equipment. The AS curve is drawn given some nominal variable, such as the nominal wage rate. In the short run, the nominal wage rate is taken as fixed. Thus, rising P implies higher profits that justify expansion of output. In the neoclassical long run, on the other hand, the nominal wage rate varies with economic conditions. (High unemployment leads to falling nominal wages -- and vice-versa.)

Summary:

Everything that is planned to be sold