OpenCitations provides two main datasets.
OpenCitations Index. The Index contain information about the citations themselves, in which the citations, instead of being considered as simple links, are treated as first-class data entities in their own right. The Index do not store metadata about the citing and cited bibliographic entities internally. Rather, these entities are identified in the Index by their unique identifiers, i.e. the OpenCitations Meta Indentifier (OMID), enabling bibliographic information to be retrieved on-the-fly upon request by means of the OpenCitations Meta API.
OpenCitations Meta. OpenCitations Meta stores and delivers bibliographic metadata for all publications involved in the OpenCitations Index.