A roadmap is a high-level visual summary that helps map out the vision as well as the direction of a specific product.
When discussing a roadmap, you are referring to a strategic plan which defines the goal or desired outcome and includes the major steps or milestones that are required for said goal to be reached. A roadmap also serves as a communication tool, a high-level document which helps keep track of the articulated strategic thinking behind the goal as well as the plan to get there.
A roadmap is a high-level visual summary that helps map out the vision as well as the direction of a specific product offering throughout a pre-specified time period. This roadmap communicates the why as well as the what behind what you are building, and it is a guiding strategic document as well as a plan for executing the product strategy.
A roadmap has several goals, including describing vision and strategy, providing a guiding document for executing the strategy, getting internal stakeholders in alignment, facilitating discussion as well as options and scenario planning and helping communicate with the external stakeholders, including the customers.
Your roadmap needs to essentially convey the strategic direction for your specific product and it also needs to tie back to the strategy for the company. The general order of what you will be building will need to be described. Furthermore, articulating the product vision, as well as the strategy, can make it a lot easier to secure executive buy-in and ensures that everyone is working towards a common goal.
This means that a roadmap will essentially include the themes, the epics, the stories and the features.
If you decide to build a roadmap down the line, you should be asking yourself a few main questions, including why you are building the product, what you are hoping to accomplish, and how it will help users.