How Web search engines work
A search engine operates, in the following order
Web crawling
Indexing
Searching
Web search engines work by storing information about many web pages, which they retrieve from the WWW itself. These pages are retrieved by a Web crawler (sometimes also known as a spider) — an automated Web browser which follows every link it sees. Exclusions can be made by the use of robots.txt. The contents of each page are then analyzed to determine how it should be indexed (for example, words are extracted from the titles, headings, or special fields called meta tags). Data about web pages are stored in an index database for use in later queries. Some search engines, such as Google, store all or part of the source page (referred to as a cache) as well as information about the web pages, whereas others, such as AltaVista, store every word of every page they find. This cached page always holds the actual search text since it is the one that was actually indexed, so it can be very useful when the content of the current page has been updated and the search terms are no longer in it. This problem might be considered to be a mild form of linkrot, and Google's handling of it increases usability by satisfying user expectations that the search terms will be on the returned webpage. This satisfies the principle of least astonishment since the user normally expects the search terms to be on the returned pages. Increased search relevance makes these cached pages very useful, even beyond the fact that they may contain data that may no longer be available elsewhere.
When a user enters a query into a search engine (typically by using key words), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text. Most search engines support the use of the boolean operators AND, OR and NOT to further specify the search query. Some search engines provide an advanced feature called proximity search which allows users to define the distance between keywords.
The usefulness of a search engine depends on the relevance of the result set it gives back. While there may be millions of webpages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others. Most search engines employ methods to rank the results to provide the "best" results first. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one engine to another. The methods also change over time as Internet usage changes and new techniques evolve.
Most Web search engines are commercial ventures supported by advertising revenue and, as a result, some employ the practice of allowing advertisers to pay money to have their listings ranked higher in search results. Those search engines which do not accept money for their search engine results make money by running search related ads alongside the regular search engine results. The search engines make money every time someone clicks on one of these ads.
Revenue in the web search portals industry is projected to grow in 2008 by 13.4 percent, with broadband connections expected to rise by 15.1 percent. Between 2008 and 2012, industry revenue is projected to rise by 56 percent as Internet penetration still has some way to go to reach full saturation in American households. Furthermore, broadband services are projected to account for an ever increasing share of domestic Internet users, rising to 118.7 million by 2012, with an increasing share accounted for by fiber-optic and high speed cable lines.[8]
Information literacy
Several conceptions and definitions of information literacy have become prevalent. For example, one conception defines information literacy in terms of a set of competencies that an informed citizen of an information society ought to possess to participate intelligently and actively in that society (from [1]).
The American Library Association's (ALA) Presidential Committee on Information Literacy, Final Report states that, "To be information literate, a person must be able to recognize when information is needed and have the ability to locate, evaluate, and use effectively the needed information" (1989).
Jeremy Shapiro & Shelley Hughes (1996) define information literacy as "A new liberal art that extends from knowing how to use computers and access information to critical reflection on the nature of information itself its technical infrastructure and its social, cultural, and philosophical context and impact." (from [2])
Information literacy is becoming a more important part of K-12 education. It is also a vital part of university-level education (Association of College Research Libraries, 2007). In our information-centric world, students must develop skills early on so they are prepared for post-secondary opportunities whether that be the workplace or in pursuit of education.
History of the concept
A seminal event in the development of the concept of information literacy was the establishment of the American Library Association's Presidential Committee on Information Literacy whose final report outlined the importance of the concept. The concept of information literacy built upon and expanded the decades-long efforts of librarians to help their users learn about and how to utilize research tools (e.g., periodical indexes) and materials in their own libraries. Librarians wanted users to be able to transfer and apply this knowledge to new environments and to research tools that were new to them. Information literacy expands this effort beyond libraries and librarians, and focuses on the learner, rather than the teacher (Grassian, 2004; Grassian and Kaplowitz, 2001, pp.14-20).
Other important events include:
1974: The related term ‘Information Skills’ was first introduced in 1974 by Zurkowski to refer to people who are able to solve their information problems by using relevant information sources and applying relevant technology (Zurkowski, 1974).
1983: A Nation at Risk: The Imperative for Education Reform
shows that we are "raising a new generation of Americans that is scientifically and technologically illiterate."
1986: Educating Students to Think: The Role of the School Library Media Program
outlines the roles of the library and the information resources in K-12 education
1987: Information Skills for an Information Society: A Review of Research
includes library skills and computer skills in the definition of information literacy
1988: Information Power: Guidelines for School Library Media Programs
1989: National Forum on Information Literacy (NFIL), a coalition of more than 90 national and international organizations, has its first meeting
1998: Information Power: Building Partnerships for Learning
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