Keywords are the essential terms or concepts that embody the main topics, ideas, and scope of a study. In a published article they usually appear directly below the abstract, and you also enter them into the journal’s online submission system. A keyword such as “circular economy,” for instance, immediately signals that a paper concerns sustainability and waste reduction.
Their job is twofold. First, they tell readers and editors what the paper is about at a glance. Second, they act as tags that help search engines and academic databases identify your manuscript and surface it to people searching for related topics. In that sense they function a little like social-media hashtags for scholarship: compact labels that connect your work to a wider conversation. Crucially, keywords are not the same as a list of the words you happen to use most; they are chosen deliberately for retrieval.
| Keywords are… | Keywords are not… |
| • Retrieval and indexing tools
• Deliberately chosen for how readers search • Concise terms or 2–4 word phrases • A bridge to adjacent topics and synonyms |
• A summary or abstract of the paper
• A random list of frequent words • Long descriptive sentences • A place to repeat the title verbatim |
Why Keywords Matter
With millions of articles published every year, even excellent research can be buried. Keywords are a primary mechanism by which your paper rises out of that pile. They matter for several concrete reasons:
- Databases and search engines scan titles, abstracts, and keywords to match articles to a query. Missing the terms your readers actually use means your paper may never appear in their results.
- Discoverability and citations are linked. Work that is easier to find is read more, and read more often leads to being cited more. Well-chosen keywords are associated with higher visibility and citation potential.
- Correct categorization. Keywords help databases file your paper under the right subject, so it reaches a relevant rather than random audience.
- Reviewer and editor matching. Many submission systems use your keywords to assign your manuscript to an appropriate editor and to locate qualified peer reviewers. Inaccurate keywords can route your paper to the wrong desk.
- For databases that sort by relevance, strategic keywords can be the difference between the first page of results and obscurity.
Treating keywords as just a box to tick at submission does your paper a disservice. A few minutes of deliberation can materially change how many people encounter your work.
How Databases and Search Engines Use Keywords
Databases are organized collections of scholarly articles drawn from many journals and publishers. Well-known examples include Scopus, Web of Science, and Google Scholar. When an article enters a database, it is indexed so that others can find it. That indexing draws on two kinds of terms:
- Author-supplied keywords: the terms you provide below the abstract and in the submission form.
- Database-derived terms: terms pulled automatically through full-text indexing or from the titles of cited references.
Some search engines, such as Google Scholar, may scan an article in its entirety. But the underlying principle is constant: if the critical terms are absent, the article is far less likely to surface. Keywords act as filters that let a database sift thousands of records down to the most relevant matches for a query.
Controlled vocabularies and MeSH
Some databases, especially in medicine, rely on controlled vocabularies: standardized term lists that provide a consistent way to find articles on a topic no matter which synonyms or abbreviations an author used. The best-known is MeSH (Medical Subject Headings), maintained by the U.S. National Library of Medicine and used by PubMed and MEDLINE. The MeSH thesaurus is also a practical source of established, popular terms. Where a controlled vocabulary exists for your field, aligning your keywords with it improves retrievability and consistency.
How to Choose the Right Keywords: A Step-by-Step Method
The quality of your search results is directly tied to the quality of your keywords. The following repeatable workflow brings together the best practice from editors, publishers, and university research guides.
Step 1: Understand the core of your study
Identify the central theme, research question, and scope of your paper. Write down the terms that capture its essence: these are usually nouns. Focus on what is genuinely central, not concepts that are barely touched.
Step 2: Mine the title and abstract
Extract the most essential terms from your title and abstract, since these sections carry the densest signal of what your paper is about. As an example, a paper titled “Impact of Nanobiosensor-Derived Lactate Monitoring on Intrapartum Hypoxia Outcomes in High-Risk Pregnancies” yields strong candidate keywords such as intrapartum hypoxia, high-risk pregnancy, nanobiosensors, lactate monitoring, and fetal acidosis.
Step 3: Brainstorm synonyms and related terms
Think about the different words other researchers might use to search for your topic, then list similar, broader, narrower, and related terms. A thesaurus, a concept map, or even describing a relevant image can help. So can asking a supervisor, a colleague, or a librarian. Keep the list beside you and keep adding to it.
Examples of useful substitutions and expansions:
- Botanical or species names → common names (Zea mays → maize; Oryza sativa → rice).
- Chemical or process terms → synonyms (degradation of a pollutant by microorganisms → bioremediation; adrenaline → epinephrine).
- Broader or narrower scope (vertebrates → mammals or primates; “renewable energy” → “sustainable energy”).
- Gene symbol in the title → full gene name as a keyword, and vice versa.
Step 4: Build a candidate pool, then narrow it
Assemble a generous pool of terms and word clusters that recur in your manuscript, keeping your target audience in mind. Then filter aggressively. Drop very general terms like “diet,” “medicine,” “technology,” “treatment”. These just bury your paper among countless others. Make them specific instead: “cancer treatment” is better, “liver cancer treatment” better still. Be cautious with newly coined terms and unusual abbreviations that few people will search.
Step 5: Prefer specific phrases over single words
Single words are often too broad and produce false matches. Two- to four-word phrases are usually more precise and effective. For a paper on leg pain, for instance, alternatives like leg cramps, muscular leg pain, or leg spasms will stand out far better than the generic word “pain.” Avoid conjunctions such as “and” within a keyword.
Step 6: Decide whether to mirror the title
Many journals automatically index the words in your title, so repeating them as keywords is a wasted opportunity. Use that space for synonyms and adjacent terms instead, so you get indexed for a wider range of searches. Some journals state this explicitly. (A handful do want overlap: always defer to the journal’s guidance.)
Step 7: Handle abbreviations carefully
Use an abbreviation only if it is well known, has a single dominant meaning, and is something researchers actually search. “ANOVA,” “PTSD,” and “HbA1c” (for a diabetes paper) are generally safe. Ambiguous ones are risky: “SDI” can mean strategic defence initiative or selective dissemination of information; “ARC” has meanings across many fields; “CGMP” could be continuous glucose monitoring program or current good manufacturing practice. When the abbreviation already appears in the title, use the spelled-out form as the keyword.
Step 8: Consider naming your study design
If the method is a defining feature of the work, include it: for example, “randomized controlled trial” or “systematic review.” Researchers frequently filter by design, so this can attract exactly the right readers.
Step 9: Use tools and controlled vocabularies
Lean on resources that reveal real search behavior: the MeSH thesaurus for medical and health topics, keyword-planning tools such as Google Keyword Planner, and the indexes of major databases. Some university libraries also offer keyword generators. These tools surface established terminology and trends rather than leaving you to guess.
Step 10: Test your keywords
Before committing, paste each term individually and in combination into the databases your field uses, such as Google Scholar and PubMed. Scan the results. If most are relevant to your study, the keyword works; if the results are off-topic, revise it. A classic trap: do not use “nursing” as a synonym for “breastfeeding,” because results will be dominated by professional nursing care: use “human lactation” instead.
Quick reference: dos and don’ts
| Do | Don’t |
| Choose article-specific terms | Default to broad or general terms |
| Use synonyms and adjacent terms | Repeat too many words already in the title |
| Pick specific 2–4 word phrases | Rely on single, vague words |
| Choose about 3–8 pertinent keywords | Overstuff with too many keywords |
| Use only unambiguous, well-known abbreviations | Use abbreviations with multiple meanings |
| Align with controlled vocabularies like MeSH | Assume which terms are standardized |
| Use planning tools and test in databases | Guess at keyword popularity |
How Many Keywords Should You Use?
There is no single universal number, but the common range is roughly three to ten, with most journals asking for about five to eight. A practical rule of thumb when your target journal is undecided is to prepare four to five strong keywords and expand from there. Whatever the count, make the selection span your main topics, relevant subdisciplines, and key methods so you cover a broad-enough spread without padding. Most importantly, the journal’s own rule overrides every general guideline: some cap the number, and some require single words rather than phrases.
| Situation | Practical guidance |
| Typical journal request | About 3–8 keywords; many clinical journals ask for 5–8. |
| Target journal not yet chosen | Prepare 4–5 effective keywords as a flexible baseline. |
| Journal sets a limit or format | Follow it exactly: it overrides any general advice. |
How and Where to Use Keywords in Your Paper
Choosing strong keywords is half the task; placing and deploying them well is the other half. Used naturally throughout the manuscript, they reinforce discoverability without harming readability.
Title and abstract
These are the first things readers and search engines see. Work your most important terms into the title and weave key terms into the abstract, since abstracts are widely accessible even when the full text sits behind a paywall. Keep the title concise and readable; balance searchable terms against clarity. (Remember the title-overlap rule above when you compile the separate keyword list.)
Across the main sections
Use your keywords and their variations naturally across the introduction, methods, results, discussion, and conclusion. Descriptive subheadings that contain key terms help readers scan and help search engines parse your structure. The watchword is naturalness: the text must still read well.
Variations and synonyms
Beyond your shortlisted list, use related terms and synonyms in the body so the paper is found by readers who phrase things differently. But make sure that the writing isn’t repetitive or spammy.
Learn from highly cited work
Look at how well-cited papers on similar topics use their keywords. If a search for your intended terms surfaces strongly relevant articles, you know the terms work; their choices may also suggest keywords you hadn’t considered.
Avoid stuffing and irrelevance
Resist the urge to cram in extra or loosely related terms. Irrelevant keywords mislead readers and can exclude your paper from the searches that matter, and overstuffing can be penalized as keyword spam. A few precise, relevant terms used strategically beat a long, padded list every time.
This article was published on August 9, 2022, and updated on June 10, 2026.