A project plan is a living document — dates shift, work estimates change, and scope evolves. Without a fixed reference point, it is impossible to answer the question: "How does our current plan compare to what we originally committed to?"
The PPM data model is built around four core concepts — Projects, Work Items, Milestones, and Baselines — with work items connected to each other through parent–child hierarchy, links, and dependencies. Understanding how these relate is the key to understanding how Raytio's project tracking works.