This survey presents the concept of Big Data. Firstly, a definition and the features of Big Data are given. Secondly, the different steps for Big Data data processing and the main problems encountered in big data management are described. Next, a general overview of an archi- tecture for handling it is depicted. Then, the problem of merging Big Data architecture in an already existing information system is discussed. Finally this survey tackles semantics (rea- soning, coreference resolution, entity linking, information extraction, consolidation, para- phrase resolution, ontology alignment) in the Big Data context.