A baseline captures a snapshot of your original estimates for the project plan before any work begins. Once project details are finalized, you can establish a project baseline by clicking “Set Baseline” on the project record.
Then, you can use the baseline data for comparison to actual work and revised schedules later in the execution phase of your project. Note that only users with Edit or Full permission for Projects can set a project baseline.
Now, the baseline data is recorded. The project record now shows a Last Baseline Date field in the header that displays the date you most recently set a baseline. If you need to reset the baseline data for a project, you can click “Set Baseline” again. The data previously stored in the baseline fields will be overwritten with the more current data.