Every Project will have some measure of uncertainty in its outcome. This means there is risk of unknown problems derailing or slowing or costing the project. This risk often spans the golden triangle of quality, schedule, and cost, but it can also extend further into things like loss of personnel, external project factors, stakeholders, change, and the like. One of your key jobs as a PM is to identify, analyze, mitigate, and manage these risks that threaten your project.
The following are links to specific posts and pages on this all-important topic of Risk Management: