science

Index term

Index term is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Index term rather than just read about it. In short: 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.

Key takeaways

Index term belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Index term to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Index term from memory before moving on to harder problems.

Reference excerpt

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. The term "descriptor" was by Calvin Mooers in 1948. It is in particular used about a preferred term from a thesaurus. The Simple Knowledge Organization System language (SKOS) provides a way to express index terms with Resource Description Framework for use in the context of the Semantic Web.

In web search engines Most web search engines are designed to search for words anywhere in a document—the title, the body, and so on. This being the case, a keyword can be any term that exists within the document. However, priority is given to words that occur in the title, words that recur numerous times, and words that are explicitly assigned as keywords within the coding. Index terms can be further refined using Boolean operators such as "AND, OR, NOT." "AND" is normally unnecessary as most search engines infer it. "OR" will search for results with one search term or another or both. "NOT" eliminates a word or phrase from the search, getting rid of any results that include it. Multiple words can also be enclosed in quotation marks to turn the individual index terms into a specific index phrase. These modifiers and methods all help to refine search terms, to better maximize the accuracy of search results.

Author keywords Author keywords are an integral part of literature. Many journals and databases provide access to index terms made by authors of the respective articles. How qualified the provider is decides the quality of both indexer-provided index terms and author-provided index terms. The quality of these two types of index terms is of research interest, particularly in relation to information retrieval. In general, an author will have difficulty providing indexing terms that characterize his or her document relative to other documents in the database.

Examples Canadian Subject Headings (CS) Library of Congress Subject Headings (LCSH) Medical Subject Headings (MeSH) Polythematic Structured Subject Heading System (PSH) Subject Headings Authority File (SWD)

See also Index (publishing) Keyword density Subject (documents) Tag (metadata) Tag cloud

References

Further reading Ferris, Anna M. (2018). "Birth of a Subject Heading". Library Resources & Technical Services. 62 (1): 16–27. doi:10.5860/lrts.62n1.16.

Worked examples

Example 1 — a first encounter with Index term

Start with the simplest possible case. Write down what Index term claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Index term before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Index term ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Index term

In research: Index term appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Index term in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Index term is common in secondary-school and first-year university syllabi. It links to neighbouring topics Information retrieval techniques, Thesauri (information retrieval), so understanding it makes those chapters shorter.
In everyday life: Look for Index term outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Index term in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Index term means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Index term out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Index term in simple terms?

Why does Index term matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Index term?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Index term.