Finance is the study of how investors allocate their assets over time under conditions of certainty and uncertainty. A key point in finance, which affects decisions, is the time value of money, which states that a dollar today is worth more than a dollar tomorrow. Finance measures the risks vs. profits and gives an indication of whether the investment is good or not. Finance can be broken into three different sub categories: public finance, corporate finance and personal finance.

http://en.wikipedia.org/wiki/Finance