A risk is an event, which is uncertain and has a negative impact on some activity.
Risk analysis is the process of quantitatively or qualitatively assessing risks. It involves estimating both the uncertainty of the risk and its impact.
Risk management is the use of risk analysis to devise management strategies to reduce risk.
In project management, these techniques are used to address the following questions:

• Will the project go over schedule? (Schedule Risk)

• Will the project overrun its budget? (Cost Risk)

• Will the output of the project fail to satisfy the goals? (Performance Risk)

At the beginning of a project and throughout its duration, the answers to these questions are unknown, but a 'yes' answer to any of them is obviously undesirable. Each of these elements should therefore be subjected to a risk analysis, to help project managers decide whether the project is in danger of failing to meet its commitments and whether or not anything can be done to improve the project's chances of success.