The introduction is the most-read section of a research paper after the abstract, and it carries a specific burden: it must convince a reader who knows the field that your study was worth doing. Many introductions fail at this not because the research is weak, but because the writing never connects the dots. They give background without arriving at a gap, or state an aim that does not follow from the background, leaving the reader to guess why the study exists. A good introduction removes that guesswork: it moves step by step from the broad field to the specific gap to the study's aim, so that by the final paragraph the study feels necessary rather than merely interesting.
This guide explains the funnel structure that most research introductions follow, shows what each part should do — background, gap, aim, and significance — and covers the common mistakes that weaken an introduction. It applies to original research articles across fields, including veterinary and animal science work submitted to journals such as the Global Journal of Veterinary and Animal Sciences.
Most research introductions follow a funnel shape. They open with the broad field and the problem it faces, narrow to the specific area of the literature where the study sits, identify the gap in that literature, and end with the aim of the present study. This shape is not a rule imposed by journals; it is a consequence of how readers think. A reader needs the broad context first to understand why the problem matters, then the narrowing to see where the study fits, then the gap to understand why a new study was needed, and finally the aim to know what the study sets out to do.
The funnel also controls length. Each stage of the funnel should be as short as it can be while doing its job: the broad opening needs one or two paragraphs, not a history of the field; the literature discussion should cover only the studies that bear on the gap; and the aim should be stated plainly in one or two sentences. Introductions that run for many pages usually suffer from a funnel that never narrows — background keeps expanding instead of converging on the gap. If your introduction feels long, the usual fix is not cutting words at random but finding the point where the narrowing should have happened and starting it sooner.
The background section establishes the problem and its importance. Open with the practical or scientific problem your study addresses, stated in terms a reader in your field recognises immediately. Then give only the context needed to understand that problem: the key facts, the scale of the issue where relevant, and the main lines of existing work. Every background sentence should pass a simple test: does the reader need this sentence to understand the gap that follows? If not, the sentence belongs in a review article, not in your introduction.
Cite as you write background, and cite the studies you actually rely on rather than secondary summaries of them. Background claims without citations look like opinion, and reviewers will check the important ones. At the same time, do not cite everything ever written on the topic: a background section with dozens of citations for a single point suggests the author has not decided which studies matter. Choose the most relevant and most rigorous studies, and let the citation list reflect judgement rather than volume. Our guide on how to write a literature review explains how to select and synthesise those studies.
Judging how much background is enough is a skill that improves with practice. A useful rule is to write the background, then delete any paragraph whose removal does not change the reader's understanding of the gap. What remains is the background the paper actually needs. Another useful check is to ask a colleague in a neighbouring area to read the introduction: if they can follow the argument to the gap without asking for more context, the background is sufficient, and if they get lost, the missing piece is usually a definition, a key finding, or a link between two ideas rather than a whole extra section.
The gap statement is the hinge on which the whole introduction turns. Everything before it builds towards it, and everything after it follows from it. State the gap explicitly, in one or two sentences, and make it specific: name what is unknown, in which population or setting, and why the existing evidence does not already answer it. Vague gap statements — "little is known about this topic" — are weak because they are almost always partly untrue and they give the reader no sense of what the study will actually add.
A strong gap statement also shows its working. It should follow from the literature you just discussed: the reader should be able to see, from the studies you cited, why the gap exists. If the gap appears from nowhere, the background has not done its job, and the reader will doubt whether the gap is real. This is why the funnel matters: the background narrows to the gap, so that when the gap is stated, it feels like the natural conclusion of the discussion rather than a claim bolted on at the end. For a full treatment of gap types and how to find one, see our guide on how to find a research gap.
After the gap, state the aim of the study plainly. The aim is a single sentence answering the question: what did this study set out to do? It should follow directly from the gap — a reader who has followed the funnel should be able to predict the aim before reading it. If the aim surprises the reader, either the gap was stated wrongly or the study drifted from its original purpose, and both possibilities need attention before submission.
Where the journal expects them, follow the aim with specific objectives or hypotheses. Objectives break the aim into the concrete steps the study takes; a hypothesis states the expected relationship where the study tests one. Keep objectives few and directly tied to the methods and results that follow — an objective with no matching result in the paper, or a result with no matching objective, signals a study that changed direction without updating its introduction. Consistency between aim, objectives, methods, and results is something reviewers check carefully.
Close the introduction with the significance of the study: who benefits if the question is answered, and how? Significance should be concrete rather than grand. A study that helps veterinarians choose a diagnostic approach in field conditions has clear significance; a study described as advancing human knowledge in general does not. Keep significance inside the evidence the study can actually provide — do not promise practical benefits the design cannot support, and do not claim the study will solve a problem it only illuminates. Reviewers trust measured significance far more than sweeping claims.
Several habits reliably weaken introductions. The first is reporting results: the introduction should not state the study's findings, except in the rare case where a journal's format asks for it. Results belong in the results section, and previewing them in the introduction removes the reader's reason to read on carefully. The second is over-claiming novelty — describing the study as the first ever of its kind without the evidence to support that claim. Unless the paper itself proves the claim, leave it out.
The third habit is excessive length, usually caused by background that never narrows or by a literature discussion that covers the whole field instead of the gap. The fourth is inconsistency: an aim that does not match the methods, or a significance claim that the results cannot support. Read the introduction against the methods and results sections before submitting, and fix any mismatch — reviewers will find it if you do not. Finally, avoid jargon and undefined abbreviations in the opening paragraphs: the introduction should be readable by any researcher in the broader field, not only by specialists in your exact sub-area.
Most authors find the introduction easier to write in two passes. In the first pass, written when the study is planned, draft the background, gap, and aim to clarify the study's purpose before data collection begins. This draft guides the design: it forces the author to state what is unknown and what the study will measure, which prevents the common problem of collecting data and only afterwards searching for a question it can answer. Treat this first draft as a working document, not a finished section.
In the second pass, written after the results are known, revise the introduction to match the study as actually conducted. Methods change, populations shift, and findings sometimes answer a slightly different question than the one originally asked. Update the gap and aim to reflect the real study, and check that every claim in the introduction is still supported by the literature and by the paper itself. An introduction that describes a study different from the one in the methods section is a frequent reviewer complaint, and it is entirely avoidable with this second pass.
Between the two passes, keep the introduction short on purpose. Resist the temptation to keep adding background as you read more papers; instead, add new studies only where they change the gap or strengthen the argument for the study. An introduction that grows with every paper you read becomes a review article, and review articles are a different genre with a different purpose. The introduction's purpose is narrower: to take the reader from the field to the gap to the aim, and then stop.
When the introduction is ready, the rest of the paper becomes easier to write, because the aim now governs the methods, the results answer the aim, and the discussion returns to the gap the introduction identified. For the full journey from manuscript to publication, see our step-by-step guide on how to publish a research paper, and for the summary that most readers see first, our guide on how to write a research abstract.
| Part | What it does | Common mistake |
|---|---|---|
| Background | Establishes the problem and its importance | A textbook history of the field that never narrows |
| Literature | Shows what is known, leading towards the gap | Covering the whole field instead of the gap |
| Gap | States specifically what is missing and why it matters | A vague claim such as "little is known" |
| Aim | States plainly what the study sets out to do | An aim the reader cannot predict from the gap |
| Significance | Explains who benefits, concretely | Grand claims the study cannot support |
These authoritative external resources explain the standards and guidance mentioned in this article:
How long should a research paper introduction be?
There is no fixed length, but most introductions for original research articles run to a few pages at most. The test is not length but structure: if the funnel narrows to a specific gap and aim, the length is right.
Should I report my results in the introduction?
Generally no. Results belong in the results section. Previewing them in the introduction removes the reader's reason to read on and is discouraged by most journals.
What is the difference between the aim and the objectives?
The aim is the single overall purpose of the study. Objectives break that purpose into the concrete steps the study takes. Both should match the methods and the results that follow.
Can I claim my study is the first of its kind?
Only if the paper itself proves it with a thorough search of the literature. Unsupported novelty claims damage credibility; reviewers check them, and a single earlier study undermines the claim.
How many citations should an introduction have?
Enough to support the key claims and show the gap follows from the literature — no more. A citation list that reflects judgement, not volume, reads as stronger to reviewers.
Should I write the introduction first or last?
Draft it early to clarify the gap and aim, but revise it last, after the results are settled. The final introduction must match the study as actually conducted, not as originally planned.