A world map is a map of most or all of the surface of 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 aesthetic 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.
A map is made using a map projection, which is any method of representing a globe on a plane. All projections distort distances and directions, and each projection distributes those distortions differently. Perhaps the most well known projection is the Mercator Projection, originally designed as a nautical chart.
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".
Early world maps cover depictions of the world from the Iron Age to the Age of Discovery and the emergence of modern geography during the early modern period. Old maps provide much information about what was known in times past, as well as the philosophy and cultural basis of the map, which were often much different from modern cartography. Maps are one means by which scientists distribute their ideas and pass them on to future generations.
Hypothetical reconstruction of the world map of Anaximander (610–546 BC)
World map according to Posidonius (150–130 BC), drawn in 1628.
Ideal reconstruction of medieval T-and-O maps (from Meyers Konversationslexikon, 1895) (Asia shown on the right)
World map in Octant projection (1514). From Leonardo da Vinci's Windsor papers.
1652 world map by Claes Janszoon Visscher
A historical map of the world by Gerard van Schagen, 1689
- the map represents state-of-the art knowledge of the time, actively collected from Portuguese sources by the makers of the Dieppe maps during the 1540s to 1560s. The presentation of Terra Australis is conventional, imagined as attaching to the Strait of Magellan. A possible sighting of Australia prior to 1560 has been discussed in scholarship but is mostly considered unlikely. The interior of Africa was at the time largely unexplored and is filled in with partially fictional geography.
- Large-Scale Distortions in Map Projections, 2007, David M. Goldberg & J. Richard Gott III, 2007, V42 N4.
- American Cartographic Association's Committee on Map Projections (1988). Choosing a World Map. Falls Church: American Congress on Surveying and Mapping. pp. 1–2.
- Thematic Maps Map Collection & Cartographic Information Services Unit. University Library, University of Washington. Accessed 27 Dec 2009.
- "History of maps and cartography". emporia.edu.
- 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