<Tr> <Td> </Td> <Td> Tourist information </Td> </Tr> <P> A good map has to compromise between portraying the items of interest (or themes) in the right place on the map, and the need to show that item using text or a symbol, which take up space on the map and might displace some other item of information . The cartographer is thus constantly making judgements about what to include, what to leave out and what to show in a slightly incorrect place . This issue assumes more importance as the scale of the map gets smaller (i.e. the map shows a larger area) because the information shown on the map takes up more space on the ground . A good example from the late 1980s was the Ordnance Survey's first digital maps, where the absolute positions of major roads were sometimes a scale distance of hundreds of metres away from ground truth, when shown on digital maps at scales of 1: 250,000 and 1: 625,000, because of the overriding need to annotate the features . </P> <P> The Earth being spherical, any flat representation generates distortions such that shapes and areas cannot both be conserved simultaneously, and distances can never all be preserved . The mapmaker must choose a suitable map projection according to the space to be mapped and the purpose of the map . </P> <P> Some maps contain deliberate errors or distortions, either as propaganda or as a "watermark" to help the copyright owner identify infringement if the error appears in competitors' maps . The latter often come in the form of nonexistent, misnamed, or misspelled "trap streets". Other names and forms for this are paper townsites, fictitious entries, and copyright easter eggs . </P>

What kind of map is used for navigation