Quantity supplied is an economic term used to describe the amount of a good or service that firms are willing and able to supply to the market at a given price point. It is an important metric for evaluating market conditions and understanding the economics of a market.

In a free market, the quantity supplied is directly tied to the price level. As the price rises, firms are more likely to produce more of a good or service since there is a larger potential profit from doing so. On the other hand, when the price falls, firms are likely to reduce the amount of a good or service they produce as the profit potential shrinks. This is known as the law of supply - as prices increase, the quantity supplied will increase, and as prices decrease, the quantity supplied will decrease.

The quantity supplied must be distinguished from the total supply, which is the sum of all the good or services provided by all the firms in a certain market. The total supply reflects the total amount available, while the quantity supplied is reflective of the amount available at that particular price point. It is important to remember that the quantity supplied is subject to change based on the various market forces at play, while the total supply is fixed.

Many factors can influence the quantity supplied in a market, including the elasticity of supply and demand, changes in input costs, and the presence of government regulation. When it comes to the elasticity of supply and demand, the quantity supplied is highly elastic if a good or service has a great many substitutes. This means that customers will be quick to find an alternative and the quantity supplied will easily adjust to the change in price. If the good or service does not have many substitutes, the quantity supplied will be less elastic, as customers will be slower to find alternatives.

Changes in input costs can also influence the quantity supplied in a market, since these will determine the amount of profit a firm can make from producing a good or service. An increase in the costs of labor, raw materials, or energy may cause firms to reduce the quantity supplied, while a decrease in these costs may encourage them to increase their production of the good or service. Additionally, government regulations or market interventions may also have an impact on the quantity supplied.

In summary, quantity supplied is the amount of a good or service that firms are willing and able to supply to the market at a given price. In a free market, higher prices tend to lead to a higher quantity supplied, since firms will be able to reap a larger profit from producing more of the good or service. On the other hand, lower prices will reduce the quantity supplied. The quantity supplied is not equal to the total supply, and is influenced by a variety of factors, including the elasticity of supply and demand, changes in input costs, and the presence of government regulation or market interventions.