Money which is running an economy lubricants are always a hot topic for discussion. Like an engine without oil, the economy also will not work without the money. However, many of us who only understand the meaning of money in the context of its form as paper money and coins. In fact, the definition of money is anything that can be accepted as a means of payment for goods and services in an economic system. In fact, in ancient times people used stone, animal skins, salt, and shells as money. At the time of the Prophet (SAW), gold coins (dinars), which comes from the Roman and silver coins (dirhams), which comes from the Persian are the two precious metals are regarded as currency. In the current era, paper money (fiat money) has become a common means of payment used in all countries in the world.

Counter-concept of Time Value of Money
Islamic economic principles which have come from both the legal sources of the Koran, Hadith and Muslim scholars thought. These fundamental values underlying the Muslim economists view the birth of thought, including reviewing the functions of money in economic life. In their opinion, the functions of money there are only two, namely: 1. as a measure of prices, and 2. means of payment. The function of money as a store of value is not recognized because it was considered something close to usury. The function of money is prohibited from actually gave birth to the theory that time value of money. Corollary, Muslim economists do not agree with this concept.

In the context of conventional economics, there are many things we can compare the technical evaluation of the project, meaning that comparisons should be made of the perception of Islam when the techniques and concepts we can not find an adequate solution in the capitalist economic system. One of these is the concept of time value of money (time value of money).

Since the first man has used various means to establish exchange of goods, in order to meet their needs. In the civilization that is still very simple, human conduct exchange needs by barter. However, this exchange entails a double coincidence of wants from the parties that this exchange. The more numerous and complex human needs, the more difficult to make exchanges so that complicates human muamalah. That's why people had been thinking of the need for a medium of exchange that can be accepted by all parties. A medium of exchange is called money.

Although at the beginning of the emergence of Keynesian economic thinking, the existence of money in the economy has not fully recognized. But along with the circulation period and in line with economic changes, the function and role of money in the economy more important that he not be separated from the economic system. This causes the berkonklusi economists that money is one important factor in determining the level of economic activity sesebuah country. At least there are two fundamental reasons why the economist's view that money is important in an economy. The first is that the money can be used to determine the amount of nominal, as the price level, and second because it also can be used as a standard to determine the amount of riel, such as the amount of riel riels output and employment.