History is the study of the past through written and oral records, although it may draw on the physical remains studied by Archaeology. Historians primarily concern themselves with processes of change – in people, practices, institutions and societies – tracing these processes through the accounts at their disposal. Many historians rely upon the collections of physical documents in archives for their analysis, while others work with the memories of living witnesses of historical events. The study of the methods employed to write about the past is known as Historiography. History is also subdivided according to spheres of social life – there is Economic History; Political History; Ecclesiastical History; Social History; the History of Science; Landscape History, and so on. It is usual for historians to specialise in one of these subfields. Some institutions simply offer a Masters in History (MA, or MPhil), while others will provide a more targeted syllabus dedicated to a particular sphere of historical enquiry, such as an MA in Political History, or an MPhil in the History of Science. Regardless of their specialism, postgraduate degrees in History provide an excellent route into the heritage sector as well as teaching. Many history graduates utilise their research skills to work in government or consulting.