Risk, in simple terms, refers to the possibility that the actual outcome that is achieved is different from the outcome that is expected. Though some bit of deviation from the expected is always expected in the actual values and the predicted, the occurrence of significant differences can create problems as it would render the process of decision making inefficient. This is because decisions are arrived at, after inputting the estimates into the decision making process, so as to determine the expected outcome. Though risk pertains to both positive as well as negative deviations from the expected value, in the field of finance, the downside risk (i.e. the risk that the actual outcome would be significantly lesser than the expected outcome) is of much more importance and concern. In the field of finance, risk pertains to the cash flows variability of a project. Risk is accounted by measuring the variance of returns and to account for the negative deviations more specifically, several measures like downside deviation; Value at Risk (VaR), etc have been introduced.
风险，简单来说，就是指所达到的实际效果是不同的结果是预期的可能性。虽然有点从预期的偏差都是预料中的实际值和预测，差异显著的发生会使决策效率低下的过程中创建的问题。这是因为抵达决定，输入估计到决策过程后，以确定预期的结果。虽然风险涉及的正面和负面的偏离期望值，在金融领域，下行风险（即风险，实际结果会显著低于预期的结果）是更重要的关注。在金融领域，风险属于一个项目的现金流的变化。风险占收益的方差测量到的负偏差，更具体地说，一些措施如下偏差；在险价值（VaR），等方面介绍了。
