The practice of history begins with evidence and with sources - so much so that availability of sources is often the key determinant of what becomes popular with historians. Whereas historians of early modern and medieval popular culture face a constant battle to find material, or else to reassess extant records creatively, those concerned with modern political history face a veritable forest of official documents - more than any one person could marshal in a lifetime. Students of history need to be aware of the scope of historical sources and the methods of historians. Moreover, each month sees new government files being released the world over, while radio, television and internet have enormously expanded the source-base for contemporary history. Therefore, it is vital that students of history are aware of the scope of historical sources, and the methods which historians use to order them.
Historians claim to master no more than a small aspect of history's true scope.
In this we are governed by the huge growth in the volume of sources available. Now, in the twenty-first century, this abundance is even more apparent.