Big Data management is playing a major role within the database research community and is posing a plethora of challenges that are of interest for both the academic side and the industrial side of the community, still reminding that this exciting research topic has been initially born within the context of the main industrial Web players (e.g., Google, Facebook, etc.). Several research issues arise here, ranging from representing Big Data to managing Big Data, from indexing Big Data to querying Big Data, from ranking Big Data to mining Big Data, etc. As orthogonal to all the outlined research challenges, Semantics of Big Data, which mainly concerns with the issue of equipping Big Data with fruitable, actionable knowledge, is a first-class axiomatic problem to deal with.
