I'm not asking what a relational database is. I'm asking what relational data is. What makes data relational? What are some examples of relational data and of non-relational data that illustrate the difference?
Edit: I now understand that there isn't anything "relational" about the data itself, and that there are advantages to representing certain data sets relationally.
Even if the question is malformed, I think that a lot of other people might have the same question, want to know the answer, google it etc. So I think it'd be useful if they come across this.