Different groups perceive the amenities and disamenities of different parts of the world and make regions according to their perception or understanding of what the world is like. Whenever geographers make a region they must be aware that other people can come up with equally valid classifications. Every effort must be made to ensure that the criterion used to define a region are such that another person using the same criterion can come up with the same set of regions. Regions should be replicable. One of the greatest aspects of geography is the effort to understand how places are interconnected and how these interconnections change with technology and over time.
Great emphasis is placed on migration, economic activity, and urbanization.
Sources of Geographical Ideas and Data Geographers use ideas and data from a wide variety of sources. In the past, field observations and the collection of data by individual research geographers was the primary process for gathering information for geographic analysis. Today, however, very few geographers do independent fieldwork. Geographers rely on major governmental efforts to gather relevant data. For example data gathered by the United States Census Bureau is the most obvious source of demographic data in the U.S. Geographers in most parts of the world rely on such compilations for the base of their analysis.