A roadmap helps to indicate outcomes (metrics that reflect business achievements)
A roadmap is a great method of displaying a strategic plan that places a project's goals and major deliverables (assignments and milestones) on a timeline.
A roadmap helps individuals and teams to navigate between two points. It is very useful in meetings with clients and stakeholders, helping better communicate with all the participants, present your strategy, and discuss major steps.
Roadmap's structure may vary from project to project, but basically it is twofold: at its most macro level, a finished graph represents an overview of a product strategy and a timeline. Other components of a roadmap fit into this larger structure.