Resource levelling is the process used to examine a project for a realistic use of resources over time and according to constraints.
It means that we have to resolve allocation conflicts and overlaps.
When generating project schedules, the manager will attempt to schedule certain tasks at the same time. When more resources are needed than are available, or perhaps one critical resource is needed in both tasks, tasks will have to be rescheduled concurrently or even sequentially to manage the constraint resulting from resource availability.
When using PlanningForce, resource levelling means resolving conflicts or over allocations in the project plan by allowing the software to calculate delays and update tasks automatically. Project management software levelling requires delaying tasks until resources are available.