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A world map is a map of most or all of the surface of the Earth. World maps form a distinctive category of maps due to the problem of projection. Maps by necessity distort the presentation of the earth's surface. These distortions reach extremes in a world map. The many ways of projecting the earth reflect diverse technical and æsthetic goals for world maps.
World maps are also distinct for the global knowledge required to construct them. A meaningful map of the world could not be constructed before the European Renaissance because less than half of the earth's coastlines, let alone its interior regions, were known to any culture. New knowledge of the earth's surface has been accumulating ever since and continues to this day.
Maps of the world generally focus either on political features or on physical features. Political maps emphasize territorial boundaries and human settlement. Physical maps show geographic features such as mountains, soil type or land use. Geological maps show not only the surface, but characteristics of the underlying rock, fault lines, and subsurface structures. Choropleth maps use color hue and intensity to contrast differences between regions, such as demographic or economic statistics.
Map projections 
A map is made using a map projection, which is any method of representing the geoid on a plane. All projections distort distances and directions, and each projection distributes those distortions differently. Perhaps the best-known world-map projection is the Mercator Projection, originally designed as a nautical chart.
Thematic maps 
A thematic map shows geographic information about one or a few focused subjects. These maps "can portray physical, social, political, cultural, economic, sociological, agricultural, or any other aspects of a city, state, region, nation, or continent".
Historical maps 
World map according to Posidonius (150-130 B.C.), drawn in 1628 A.D.
See also 
- American Cartographic Association's Committee on Map Projections (1988). Choosing a World Map. Falls Church: American Congress on Surveying and Mapping. pp. 1–2.
- Large-Scale Distortions in Map Projections, 2007, David M. Goldberg & J. Richard Gott III, 2007, V42 N4.
- Thematic Maps Map Collection & Cartographic Information Services Unit. University Library, University of Washington. Accessed 27 Dec 2009.
Further reading 
- Edson, Evelyn (2011). The World Map, 1300–1492: The Persistence of Tradition and Transformation. JHU Press. ISBN 1421404303
- Harvey, P. D. A. (2006). The Hereford world map: medieval world maps and their context. British Library. ISBN 0712347607
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