Baseline is a simple concept in project scheduling. If you are using scheduling software like Primavera, MS Project or any other, you will need to create a baseline before you enter actual work progress in the software.
So what really the baseline is?
What is Baseline?
Baseline is really a copy of your planning, which includes your activities, their attributes like duration, dates and resources and costs. So why do we need to create a copy?
The actual reason is that we create baseline so that we could compare the actual progress with something (original plan).
You might ask that we already had a plan so why we would create its copy for comparison with actual progress. Well, in fact your planned data gets overwritten with the actual data that you enter. For example, once you enter actual start date for an activity, this date is written over your original start date. So then we have no original data to compare the actual data with. That's the reason we need to create copy of the plan.
How Do You Create Baseline?
In Primavera, baseline is created from Project menu -> Maintain Baseline. There you click Add and click OK to create a baseline. When you click Add, you will even see an option that says copy the project as a baseline.
If you're using MS Project, you can create baseline at Project tab -> Baseline -> Baseline 0 -> Click OK.
Now you know what baseline is. You may like to learn Primavera as it is globally used for project scheduling and here you can learn about the benefits that this software offers.