See the global map illustration.
It is the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
It is the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
It is the southern part of the New World. In other words, Central and South America.
It includes sub-Saharan Africa (south of 30 degrees north) and Madagascar.
It is the oriental region of the world. In other words, India and southeast Asia.
It includes Australia, New Zealand, Tasmania, New Guinea and associated islands.
That include islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.