Data management refers to the storage, access, and preservation of research data. Data management practices cover the entire lifecycle of the data, from planning the investigation to conducting it, and from backing up data as it is created and used to long term preservation of data deliverables after the research investigation has concluded.
If you are generating and/or using data in your research, a well-thought out approach to data management will save you time and frustration, maximize the impact of your work, and is a responsible research practice.