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Subject Term
In information retrieval, an index term (also known as subject term, subject heading, descriptor, or keyword) is a term that captures the essence of the topic of a document. Index terms make up a controlled vocabulary for use in bibliographic records. They are an integral part of bibliographic control, which is the function by which libraries collect, organize and disseminate documents. They are used as keywords to retrieve documents in an information system, for instance, a catalog or a search engine. A popular form of keywords on the web are tags, which are directly visible and can be assigned by non-experts. Index terms can consist of a word, phrase, or alphanumerical term. They are created by analyzing the document either manually with subject indexing or automatically with automatic indexing or more sophisticated methods of keyword extraction. Index terms can either come from a controlled vocabulary or be freely assigned. Keywords are stored in a search index. Common words li ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Information Retrieval
Information retrieval (IR) in computing and information science is the process of obtaining information system resources that are relevant to an information need from a collection of those resources. Searches can be based on full-text or other content-based indexing. Information retrieval is the science of searching for information in a document, searching for documents themselves, and also searching for the metadata that describes data, and for databases of texts, images or sounds. Automated information retrieval systems are used to reduce what has been called information overload. An IR system is a software system that provides access to books, journals and other documents; stores and manages those documents. Web search engines are the most visible IR applications. Overview An information retrieval process begins when a user or searcher enters a query into the system. Queries are formal statements of information needs, for example search strings in web search engines. In inf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tag Cloud
A tag cloud (also known as a word cloud, wordle or weighted list in visual design) is a visual representation of text data, which is often used to depict keyword metadata on websites, or to visualize free form text. Tags are usually single words, and the importance of each tag is shown with font size or color. When used as website navigation aids, the terms are hyperlinked to items associated with the tag. History In the language of visual design, a tag cloud (or word cloud) is one kind of "weighted list", as commonly used on geographic maps to represent the relative size of cities in terms of relative typeface size. An early printed example of a weighted list of English keywords was the "subconscious files" in Douglas Coupland's ''Microserfs'' (1995). A German appearance occurred in 1992. The specific visual form and common use of the term "tag cloud" rose to prominence in the first decade of the 21st century as a widespread feature of early Web 2.0 websites and blogs, used ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tag (metadata)
In information systems, a tag is a keyword or term assigned to a piece of information (such as an Internet bookmark, multimedia, database record, or computer file). This kind of metadata helps describe an item and allows it to be found again by browsing or searching. Tags are generally chosen informally and personally by the item's creator or by its viewer, depending on the system, although they may also be chosen from a controlled vocabulary. Tagging was popularized by websites associated with Web 2.0 and is an important feature of many Web 2.0 services. It is now also part of other database systems, desktop applications, and operating systems. Overview People use tags to aid classification, mark ownership, note boundaries, and indicate online identity. Tags may take the form of words, images, or other identifying marks. An analogous example of tags in the physical world is museum object tagging. People were using textual keywords to classify information and objects long b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subject (documents)
In library and information science documents (such as books, articles and pictures) are classified and searched by subject – as well as by other attributes such as author, genre and document type. This makes "subject" a fundamental term in this field. Library and information specialists assign subject labels to documents to make them findable. There are many ways to do this and in general there is not always consensus about which subject should be assigned to a given document. To optimize subject indexing and searching, we need to have a deeper understanding of what a subject is. The question: "what is to be understood by the statement 'document A belongs to subject category X'?" has been debated in the field for more than 100 years (see below) Theoretical view Charles Ammi Cutter (1837–1903) For Cutter the stability of subjects depends on a social process in which their meaning is stabilized in a name or a designation. A subject "referred ..to those intellections ..that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keyword Density
Keyword density is the percentage of times a keyword or phrase appears on a web page compared to the total number of words on the page. In the context of search engine optimization, keyword density can be used to determine whether a web page is relevant to a specified keyword or keyword phrase. In the late 1990s, the early days of search engines, keyword density was an important factor in page ranking. However, as webmasters discovered how to implement optimum keyword density, search engines began giving priority to other factors beyond the direct control of webmasters. Today, the overuse of keywords, a practice called keyword stuffing, will cause a web page to be penalized. The formula to calculate your keyword density on a web page for SEO purposes is (Nkr / Tkn) * 100, where Nkr is how many times you repeated a ''specific keyword,'' and Tkn the ''total words'' in the analyzed text. The result is a keyword density value. When calculating keyword density, ignore html tags and othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Index (publishing)
An index (plural: usually indexes, more rarely indices; see below) is a list of words or phrases ('headings') and associated pointers ('locators') to where useful material relating to that heading can be found in a document or collection of documents. Examples are an index in the back matter of a book and an index that serves as a library catalog. An index differs from a word index, or ''concordance'', in focusing on the subject of the text rather than the exact words in a text, and it differs from a table of contents because the index is ordered by subject, regardless of whether it is early or late in the book, while the listed items in a table of contents is placed in the same order as the book. In a traditional ''back-of-the-book index'', the headings will include names of people, places, events, and concepts selected as being relevant and of interest to a possible reader of the book. The indexer performing the selection may be the author, the editor, or a professional inde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Subject Headings Authority File
The or SWD (translated as ''Subject Headings Authority File'') is a controlled vocabulary index term system used primarily for subject indexing in library catalogs. The SWD is managed by the German National Library (DNB) in cooperation with various library networks. The inclusion of keywords in the SWD is defined by (RSWK) (English: Rules for the keyword catalogue). Similar authority systems in other languages include the Library of Congress Subject Headings (LCSH) and the (). Since April 2012 the SWD is part of the (GND) (English: Integrated Authority File). Scope The SWD has about 600,000 descriptors and 700,000 non-descriptors (synonyms and quasi-synonyms) as well as synonymous descriptor chains with references to a descriptor. Its growth rate is about 5.5% per year. About three-quarters of the descriptors refer to individual concepts (language identifier, person, entity, title, ethnography etc.) and a quarter are abstract concepts. Linking using hierarchical (about 115, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polythematic Structured Subject Heading System
Polythematic structured-subject heading system (abbreviated as PSH from the Czech ''Polytematický Strukturovaný Heslář'') is a bilingual Czech–English controlled vocabulary of subject headings developed and maintained by the National Technical Library (the former State Technical Library) in Prague. It was designed for describing and searching information resources according to their subject. PSH contains more than 13,900 terms, which cover the main fields of human knowledge. Because of its release in SKOS, PSH can be used not only for describing documents in a library, but also for indexing web pages. Everyone can use PSH for free. PSH is a part of the Linked Open Data cloud diagram (LOD cloud diagram). The image of the LOD cloud diagram shows datasets that have been published in Linked Data format, by contributors to the Linked Open Data community project and other individuals and organisations. History and development The PSH preparation project started in 1993, supp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medical Subject Headings
Medical Subject Headings (MeSH) is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences. It serves as a thesaurus that facilitates searching. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed article database and by NLM's catalog of book holdings. MeSH is also used by ClinicalTrials.gov registry to classify which diseases are studied by trials registered in ClinicalTrials. MeSH was introduced in the 1960s, with the NLM's own index catalogue and the subject headings of the Quarterly Cumulative Index Medicus (1940 edition) as precursors. The yearly printed version of MeSH was discontinued in 2007; MeSH is now available only online. It can be browsed and downloaded free of charge through PubMed. Originally in English, MeSH has been translated into numerous other languages and allows retrieval of documents from different origins. Structure MeSH vocabulary is divi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Library Of Congress Subject Headings
The Library of Congress Subject Headings (LCSH) comprise a thesaurus (in the information science sense, a controlled vocabulary) of subject headings, maintained by the United States Library of Congress, for use in bibliographic records. LC Subject Headings are an integral part of bibliographic control, which is the function by which libraries collect, organize, and disseminate documents. It was first published in 1898, a year after the publication of Library of Congress Classification (1897). The last print edition was published in 2016. Access to the continuously revised vocabulary is now available via subscription and free services. Subject headings are normally applied to every item within a library's collection and facilitate a user's access to items in the catalog that pertain to similar subject matter, in order to save time finding items of related subject matter. Only searching for items by 'title' or other descriptive fields, such as 'author' or 'publisher', would take more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadian Subject Headings
Canadian Subject Headings (CSH) is a list of subject headings in the English language, using controlled vocabulary, to access and express the topic content of documents on Canada and Canadian topics. Library and Archives Canada publishes and maintains CSH on the Web. Prior to the merger of the National Library of Canada and the National Archives of Canada, the National Library of Canada published a print version of CSH. Université Laval also publishes Répertoire_de_vedettes-matière_de_l'Université_Laval, Répertoire de vedettes-matière (RVM), a list intended to provide access to Canadian subject headings in the French language. See also * Faceted Application of Subject Terminology (FAST), a simplified syntax of LCSH * Library of Congress Subject Headings (LCSH) * Subject Headings Authority File (SWD; german: Schlagwortnormdatei) * (french: Répertoire d'autorité-matière encyclopédique et alphabétique unifié) * Répertoire de vedettes-matière de l'Université Laval (RVM) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
