Contemporary history issues

What does contemporary mean in history?
Contemporary history, in English-language historiography, is a subset of modern history that describes the historical period from approximately 1945 to the present..
The major challenges to historical research revolve around the problems of sources, knowledge, explanation, objectivity, choice of subject, and the peculiar problems of contemporary history.
Sources The problem of sources is a serious challenge to the historian in the task of reconstructing the past.

What does contemporary mean in history?