Every currently or recently governing administration this atlas tracks by name, one entity per government or supreme leadership, organized below by constitutional form: whether the chief executive answers to a legislature, is separately elected, shares power across both, holds office under a single ruling party, under religious or supreme-leader authority, under a monarch, under a transitional or military council, or under a collegial directorate. Belongs here: a named administration, presidency, supreme leadership or transitional council (the Biden Administration, the Starmer Government, the Khamenei Supreme Leadership). Does not belong here: the country itself, which is a country entity, the abstract system of government a given administration exemplifies, which is a systemofgovernment entity, or the institution the government sits within, such as a legislature or party, which is an institution entity.
Enter a year to compare these entries as the atlas records them at that moment. Leave it empty for the present. A year before the common era is entered with a minus sign, so 44 BCE is minus 44.