The word 'data' can mean many things to many people, so defining context is important to conversations. We define research data as:
"Units of information observed, collected, or created in the course of research"
Erway, Ricky. 2013. Starting the Conversation: University-wide Research Data Management Policy. Dublin, Ohio: OCLC Research. http://www.oclc.org/content/dam/research/publications/library/2013/2013-08.pdf.
Data Management is the process by which you control your data. For research data, it's knowing what you have, where and how you got it, annotating and documenting it, keeping it secure and intact, sharing it, getting credit for sharing, and/or preserving it in an archive.
Researchers manage their data in order to:
For examples of what happens when data is not managed correctly, Retraction Watch details many cases.
For a great discussion on why research data is so important watch this TEDx Talk, Rethinking Research Data by Kristen Briney.