Abstract, Lay Summary or Plain Language Summary: The Difference
What separates an abstract, a lay summary and a plain language summary, drawn from real journal, funder and regulator rules. It includes a side-by-side table and one hypothetical finding written all three ways.
You finish the abstract, trim it to the word limit and paste it into the submission form. Then the next box asks for an "author summary". The grant form wants a "project narrative". A trial sponsor mentions a "lay summary".
They sound like the same thing written four times. They are close, but not identical, and the differences decide who reads each one and whether it gets sent back.
The Short Version
An abstract is written for your peers and for readers close to your field. A plain language summary and a lay summary are both written for people outside it.
The last two terms overlap so much that people use them interchangeably. What actually changes is who asks for it, how long they allow, and where it ends up.
What Each One Is
The abstract
The abstract is the technical summary that travels with your paper. At the time of writing (October 2026), PLOS Computational Biology's submission guidelines say it must not exceed 300 words, should mention techniques without methodological detail, should summarize the most important results, and should not include citations.
Funders describe the same audience. NIH's advice on application sections asks for a Project Summary/Abstract written at a level informative to others in the same or related fields and understandable to a science-literate reader.
The plain language summary
A plain language summary (PLS) is a version for people outside your field. Taylor & Francis's quick guide describes a text PLS that shares the article's DOI, has a recommended length of 250 words or less, goes through scientific peer review and appears after the abstract on the article page.
The same guide describes a second, larger format: a Plain Language Summary of Publication, which has its own DOI, mixes text and images, runs up to 3000 words and has its own authors, including at least one from the original article.
Review publishers use the term too. Cochrane's style manual describes its plain language summary as a standalone summary of a review, written in plain English, that briefly describes the key question and findings and avoids technical terms and jargon.
The lay summary
You also meet the term "lay summary" in regulatory rules. The clearest example is clinical trials in the EU.
Article 37 of the EU Clinical Trials Regulation (the copy on legislation.gov.uk, derived from EUR-Lex) says that, irrespective of the outcome, within one year of the end of a trial in all Member States concerned, the sponsor submits a summary of the results to the EU database, accompanied by a summary written in a manner understandable to laypersons. Its content is set out in Annex V. Where scientific reasons detailed in the protocol make one year impossible, the summary is submitted as soon as it is available, and the protocol has to say when and why. The European Commission's page on the Regulation confirms it has applied since 31 January 2022.
The cousins: author summary and project narrative
Some requests use their own names for the same idea. PLOS Computational Biology asks every research article for an Author Summary: a 150 to 200 word non-technical summary that follows the abstract, is written in the first person, is distinct from the scientific abstract, and is meant for both scientists and non-scientists.
NIH asks for a Project Narrative that communicates the project's public health relevance in plain language understandable by a general audience. NIH also notes that if the award is funded, both the Project Summary/Abstract and the Project Narrative are shared through RePORTER, so treat them as public text.
Side by Side
The examples in this table come from the sources above, at the time of writing (October 2026). Your journal or funder may set different numbers, so always check theirs.
| Abstract | Plain language summary | Lay summary | |
|---|---|---|---|
| Who asks (examples above) | Journals, funders | Journals, review publishers | Regulators, such as for EU clinical trials |
| Main reader | Peers and science-literate readers | People outside your field | Laypersons (the EU Regulation's word) |
| Example length | Up to 300 words (PLOS Computational Biology) | 250 words or less (Taylor & Francis text PLS) | Set by the requirement (EU trials: content in Annex V) |
| Tone | Technical, compact, no citations | Plain English, no jargon | Plain, assumes no background |
| Where it lives | With the article | After the abstract on the article page | Wherever the requester publishes it, such as the EU trials database |
One Finding, Written Three Ways
Here is a hypothetical example, not a real study. Say you have a psychology paper testing whether a 10-minute breathing exercise before a midterm changes how anxious first-year students feel going in.
Abstract sentence: "In a randomized study of first-year undergraduates, a 10-minute paced-breathing exercise before a midterm reduced self-reported state anxiety relative to a reading control, with no difference in exam scores."
Plain language summary sentence: "We asked first-year students to do either a short breathing exercise or some reading before a midterm. The students who did the breathing exercise said they felt less anxious going in, but their marks were about the same."
Lay summary for participants: "Thank you for taking part. We wanted to know if a short breathing exercise helps students feel calmer before an exam. Students who did it said they felt calmer. It did not change their marks."
Notice what moves. The abstract leads with design. The plain version leads with what people did and felt. The lay summary leads with the reader's own part in it and drops every term that needs a definition.
Which One to Write First
Write the abstract for your peers, then write one plain version of about 150 to 250 words that you can adapt for each request: author summary, PLS, lay summary or narrative. Check each requester's length, voice and placement rules before you paste it in.
If you want a step-by-step method for the plain version, this guide to writing a plain language summary walks through it with a before and after.
Where Amplify Fits
A plain summary is text, and some readers would rather watch or listen. Amplify takes the PDF you upload, and nothing else, and makes four formats for one paper: a video abstract of about 3 minutes, a 45 to 60 second vertical short, an audio brief in English plus 21 more languages on request, and a one-page print-ready infographic.
Each format arrives as three variants you can edit line by line, a person reviews every format before release, and nothing publishes until you approve it. Every artifact carries the title, the authors and a link back to the paper of record.
Amplify does not replace the summary your journal or funder asks for, and it does not claim to meet their specification. If you want to submit any of it to a journal, check the journal's specs and AI policy, and ask the editor if you are unsure.
Keep the Plain Version Close
Once you have one good plain version of your finding, you will reuse it more often than the abstract: in grant reports, on your profile page, in an email to a journalist. Write it while the paper is fresh.
Quick answers
What is the difference between a lay summary and an abstract?
An abstract is written for readers in your field or close to it, while a lay summary is written for people outside it. NIH, for example, asks for a project abstract understandable to a science-literate reader, and a separate narrative in plain language for a general audience. The audience changes the vocabulary, the detail and what you lead with.
How long should a plain language summary be?
It depends on who asks, so check their rules. At the time of writing (October 2026), Taylor & Francis recommends 250 words or less for a text plain language summary, and PLOS Computational Biology asks for a 150 to 200 word non-technical author summary. A standalone plain language summary of a publication can run much longer.
Is a lay summary the same as a plain language summary?
In practice the two terms overlap heavily: both are written for people outside your field, in plain words, without jargon. The real differences come from who asks. A journal sets the length and placement of its plain language summary, while a regulator that asks for a lay summary, such as for EU clinical trials, sets its own content rules.
Do clinical trials in the EU need a lay summary of results?
Yes, for trials under the EU Clinical Trials Regulation. Whatever the outcome, Article 37 says the sponsor submits a summary of results to the EU database within one year of the end of the trial in all Member States concerned, unless the protocol justifies a later date for scientific reasons. It must come with a summary understandable to laypersons, as set out in Annex V.
