A gateway on the web is a website intended to direct users to other preselected websites containing information on a particular topic. It can also refer to a computer that acts as a message router on the internet
University librarians often set up gateways for particular areas of study, although they may be set up by anyone with sufficient expertise in a topic. Gateways may be fairly general, such as a gateway site for sciences, or more specific, such as a gateway for particle physics.
Professional or vocational bodies may also develop gateways useful to their members, as may hobby organisations. A well-known gateway for people interested in family history and genealogy is Cyndi's List. This is updated by volunteers who notify new links relevant to topics of interest such as seventeenth and eighteenth century ships' passenger lists, local history websites, lists of names of war veterans, and so on.
19.8.11
4.2.1 Search engines: what are they?
The computer application that facilitates finding things on the web is known as a search engine. This is an application that serves a similar function to an index in a book. Figure 9(a) shows the home page of a typical search engine called Google.
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| Figure 9(a) The interface to the Google search engine |
4.2 Finding information: the web
The web is a vast storehouse of ever changing, linked information on subjects as diverse as dog breeding, astronomy, tiddlywinks, and coping with bereavement.
A browser, like Internet Explorer, is used to access the web. However, given that the web contains literally billions of words of text, how would you find information on, say, the Open University?
A browser, like Internet Explorer, is used to access the web. However, given that the web contains literally billions of words of text, how would you find information on, say, the Open University?
The internet and the web: what's the difference?
People sometimes confuse the internet and the World Wide Web.
The internet refers to the physical interconnection of large numbers of smaller data communications networks to form a huge, publicly accessible ‘network of networks’. Thus the internet carries electronic mail (email), hosts chat rooms and bulletin boards, enables the transfer of files, and is the physical basis for supporting the World Wide Web.
The web is the collection of linked data stored on the internet which is accessed using a browser.
The internet refers to the physical interconnection of large numbers of smaller data communications networks to form a huge, publicly accessible ‘network of networks’. Thus the internet carries electronic mail (email), hosts chat rooms and bulletin boards, enables the transfer of files, and is the physical basis for supporting the World Wide Web.
The web is the collection of linked data stored on the internet which is accessed using a browser.
4.1.3 Global positioning system (GPS)
These days, it is possible to buy a device known as a global positioning system (GPS) to tell you where you are. Receivers are made for aircraft, ships, ground vehicles, and (as the one shown in Figure 6) for carrying in the hand.
Examples of applications for GPS are:
Examples of applications for GPS are:
- navigation;
- surveying, and establishing the shortest distance between two points (a line of sight along the ground is no longer necessary for precise positioning, so greater distances, with features such as hills obscuring the line of sight, can be surveyed much more easily);
- plate tectonic studies (seeing how large areas of the earth's surface move relative to each other).
4.1.2 Geographical data
Modern maps are now mostly assembled by computers using very large collections of geographical data, such as latitude, longitude, altitude, roads and towns. Collections of data like this (stored in databases) aim to eliminate the need to duplicate data. The data in databases is described in symbols that the computer can handle, i.e. numbers. Even the names of features are symbolised using numbers.
If I were trying to tell you the way to a particular street in a town, using only the numbers that a computer uses for geographical data, they would be meaningless to you. Even if you knew the meaning of the individual symbols, there would be too many of them for you to make sense of.
Since maps are constructed from layers of data, it's possible to leave out some layers in order to achieve a particular purpose, or to substitute other layers to achieve a different purpose. For example, features such as roads, buildings and boundaries can be left out in order to produce a map of interest to certain types of geographer; or population figures can be transformed into appropriate symbols to produce a map of interest to, say, an epidemiologist studying the spread of disease.
Map users like hikers, drivers, pilots and sailors need to have a much more understandable version of geographical data. They might use a map printed on a large sheet of paper, such as one of the Ordnance Survey maps of the UK. However, paper maps have their drawbacks. For example, they require a user to learn how to read them, they don't show the user where he or she is, and they need to be unfolded and refolded.
This highlights a very important theme of this unit: fitness-for-purpose. A physical geographer wants certain things from a map (e.g. topographical contour lines) and will probably want to see geographically important features such as soil types. A hydrologist will be more interested in a map that emphasises bodies of water and watersheds. Ramblers want to see footpaths and field boundaries. Drivers want to see roads, junctions and streets in towns.
If I were trying to tell you the way to a particular street in a town, using only the numbers that a computer uses for geographical data, they would be meaningless to you. Even if you knew the meaning of the individual symbols, there would be too many of them for you to make sense of.
Since maps are constructed from layers of data, it's possible to leave out some layers in order to achieve a particular purpose, or to substitute other layers to achieve a different purpose. For example, features such as roads, buildings and boundaries can be left out in order to produce a map of interest to certain types of geographer; or population figures can be transformed into appropriate symbols to produce a map of interest to, say, an epidemiologist studying the spread of disease.
Map users like hikers, drivers, pilots and sailors need to have a much more understandable version of geographical data. They might use a map printed on a large sheet of paper, such as one of the Ordnance Survey maps of the UK. However, paper maps have their drawbacks. For example, they require a user to learn how to read them, they don't show the user where he or she is, and they need to be unfolded and refolded.
This highlights a very important theme of this unit: fitness-for-purpose. A physical geographer wants certain things from a map (e.g. topographical contour lines) and will probably want to see geographically important features such as soil types. A hydrologist will be more interested in a map that emphasises bodies of water and watersheds. Ramblers want to see footpaths and field boundaries. Drivers want to see roads, junctions and streets in towns.
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