Price in economics and business is the result of an exchange and from that trade we assign a numerical monetary value to a good, service or asset. If Alice trades Bob 4 apples for an orange, the price of an orange is 4 apples. Inversely, the price of an apple is 1/4 oranges.

Price is only part of the information we get from observing an exchange. The other part is the volume of the goods traded per unit time, called the rate of purchase or sale. From this additional information we understand the extent of the market and the elasticity of the demand and supply.

The concept of price is central to microeconomics where it is one of the most important variables in resource allocation theory (also called price theory). Price is also central to marketing where it is one of the four variables in the marketing mix that business people use to develop a marketing plan.

In general terms price is the result of an exchange or transaction that takes place between two parties and refers to what must be given up by one party (i.e., buyer) in order to obtain something offered by another party (i.e., seller).

Yet this view of price provides a somewhat limited explanation of what price means to participants in the transaction. In fact, price means different things to different participants in an exchange:

Example - Price is commonly confused with the notion of cost as in “I paid a high cost for buying my new plasma television”. Technically, though, these are different concepts. Price is what a buyer pays to acquire products from a seller. Cost concerns the seller's investment (e.g., manufacturing expense) in the product being exchanged with a buyer. For marketing organizations seeking to make a profit the hope is that price will exceed cost so the organization can see financial gain from the transaction. Finally, while product pricing is a main topic for discussion when a company is examining its overall profitability, pricing decisions are not limited to for-profit companies. Not-for-profit organizations, such as charities, educational institutions and industry trade groups, also set prices, though it is often not as apparent. For instance, charities seeking to raise money may set different “target” levels for donations that reward donors with increases in status (e.g., name in newsletter), gifts or other benefits. While a charitable organization may not call it a price in their promotional material, in reality these donations are equivalent to price setting since donors are required to give a contribution in order to obtain something of value

Definition - Economic Theory

In ordinary usage, price is the quantity of payment or compensation for something. People may say about a criminal that he has 'paid the price to society' to imply that he has paid a penalty or compensation. They may say that somebody paid for his folly to imply that he suffered the consequence.

Economists view price as an exchange ratio between goods that pay for each other. In case of barter between two goods whose quantities are x and y, the price of x is the ratio y/x, while the price of y is the ratio x/y.