Research data refers to a resource produced or utilized in scientific or artistic research that can be used to validate and, if necessary, repeat research results. Data are typically written text, images, sound or video recordings, or numerical data, but they can also include physical objects. Research data can be in a digital, analogue or physical format.
Please note that research literature can be research data only if they are the subject of your analysis, for example when you are doing a literature analysis. The research outputs of your research, such as your thesis, are not research data neither.
It is easy to categorize the data in three groups:
You are responsible for the data you collect or produce (groups 1 & 2).
When using previously collected existing data (group 3) you are responsible for making sure you have the right to use the data. You must follow the guidelines given by the person or organization that owns, preserves or has published the data, such as an archive, a library or a museum.