A Data Management Plan is a formal document you create at the start of your project which describes all aspects of your data.
It allows you to document your strategy for managing your research data. It reflects your data management decisions and can also be used to record questions and items for action. It's a living document and can be updated as your project develops and your data management strategy is refined.
If you are working in a team, a data management plan can be used to document individual responsibilities and make sure everyone has a shared understanding. It is also a useful document for reporting to funding bodies.
Creating a data management plan can help you better prepare for your research at the beginning of a project, but it's never too late in the research lifecycle to document a plan.
The main components of a data management plan:
The University of Adelaide have created a good example of a Data Management Plan template