Introduction vs Literature Review in a Research Paper: What Is the Difference?

Key Takeaways

• The introduction states the research problem, objectives, and scope of a study, while the literature review critically analyzes prior published work related to that problem.
• The introduction is brief and forward-looking; the literature review is longer, backward-looking, and organized around themes, methods, or chronology rather than the study itself.
• An introduction is usually 400 to 1,000 words, while a literature review can run 1,000 to 5,000 words or form its own chapter in a thesis or dissertation.
• The literature review must identify a research gap; the introduction then uses that gap to justify why the current study is needed.

Glossary of Key Terms

Term	Definition
Introduction	The opening section of a paper that states the problem, purpose, scope, and structure of the study.
Literature review	A critical, organized survey of prior published work relevant to the research topic.
Research gap	A question, method, or population that existing studies have not yet addressed adequately.
Synthesis	Combining findings from multiple sources into a single, organized discussion rather than listing them one by one.
Theoretical framework	The set of concepts and theories used to explain and interpret the research problem.
Thematic review	A literature review organized by topic or theme rather than by publication date.
Citation density	How frequently a section references outside sources relative to its total length.

What Is an Introduction in a Study?

An introduction is the opening section of a research paper, thesis, or dissertation. It tells the reader what problem the study addresses, why that problem matters, and how the rest of the document is organized. Most introductions move from a general statement about the field to a specific, narrow research question, a pattern often called a funnel structure.

A typical introduction includes the research problem, the study’s objectives, a brief mention of scope or method, and a short preview of upcoming sections (especially in economics). In some of the humanities, the final paragraph states the thesis or the specific contribution the study makes, so a reader who reads only that paragraph still understands the paper’s purpose.

Core Elements of an Introduction

• An opening statement that establishes why the topic matters.
• A clear statement of the research problem or question.
• The objectives or aims of the study.
• A brief note on scope, method, or approach.
• A thesis statement or summary of the study’s contribution.
• An outline of how the rest of the document is organized.

Because the introduction is meant to orient rather than argue in detail, most of its claims are supported with only 1 or 2 citations each, saving deeper citation work for the literature review that follows.

What Is a Literature Review?

A literature review is a structured, critical survey of published work related to the research topic. Its purpose is to show what is already known, where studies agree or disagree, which methods have been used, and what remains unanswered. Unlike a simple summary, a strong literature review synthesizes sources into themes rather than describing each study 1 by 1.

In journal articles, the literature review is often short and woven into the introduction or a dedicated subsection. In theses and dissertations, it usually forms an entire chapter, citing dozens or even hundreds of sources and closing with a clearly stated research gap that the current study will fill.

Core Elements of a Literature Review

• An organizing structure, such as by theme, method, or chronology.
• A synthesis of findings across multiple studies, not a list of summaries.
• A discussion of agreements, contradictions, and debates in the field.
• An evaluation of the strengths and limitations of prior methods.
• A closing statement that identifies the research gap.

Why Do Writers Confuse the Introduction and Literature Review?

Writers confuse the two because both sections appear early in a study and both discuss prior context before the methods section begins. It is easy to let a paragraph that should introduce the topic turn into a summary of studies, or let the literature review drift into stating the paper’s own thesis.

Formatting conventions add to the confusion. Some journals list ‘Introduction’ and ‘Literature Review’ as 2 separate headings, some combine a short literature review into the introduction, and others place a full literature review as a distinct chapter after the introduction, especially in theses. Checking the target journal’s author guidelines before drafting removes most of this ambiguity.

Example Sentences: Introduction vs Literature Review

Comparing short examples side by side clarifies the distinction while drafting. The left-hand examples critically discuss prior studies in depth, while the right-hand examples state the current study’s own purpose or contribution.

Literature review-style sentence	Introduction-style sentence
Smith (2019) and Lee (2021) reached opposite conclusions on this variable, suggesting a methodological inconsistency.	This study resolves that inconsistency using a standardized measurement protocol.
Three separate frameworks have been proposed to explain this phenomenon, each with distinct limitations.	This paper proposes a fourth framework that addresses the limitations of the first 3.
Most studies before 2018 relied on small, single-site samples with low statistical power.	This research uses a multi-site sample of 1,200 participants to address that limitation.
Qualitative and quantitative studies in this area rarely cite each other directly.	This paper bridges both traditions using a mixed-methods design.

Key Differences Between Introduction and Literature Review

Aspect	Introduction	Literature review
Main purpose	States the research problem and the study’s contribution	Critically surveys and synthesizes prior work
Focus	What this study will do	What prior studies have found and debated
Position	First section of the document	After the introduction, or as its own chapter
Tone	Argumentative and forward-looking	Analytical and evaluative
Typical length	400 to 1,000 words	1,000 to 5,000 or more words
Includes thesis	Yes, usually in the final paragraph	No, but ends with a gap statement
Citation density	Low to moderate	Very high

Structural and Content Differences

Structure

The introduction follows a funnel shape, narrowing from a broad topic to a specific research question in 4 to 6 paragraphs. The literature review is usually organized thematically, grouping studies by concept, variable, or method rather than listing them in the order they were published, though a chronological structure is used when tracing how a field developed over time.

Content

The introduction contains original framing about why the study exists now. The literature review contains detailed, cited discussion of other researchers’ work, including their methods, findings, and limitations. A simple test is to check whether a paragraph is evaluating someone else’s study in depth, which belongs in the literature review, or stating this study’s own aim, which belongs in the introduction.

Audience Expectation

Readers expect the introduction to answer why this study exists and what problem it solves. They expect the literature review to answer what is already known and where the gaps are. Keeping these 2 questions distinct while drafting prevents the sections from repeating the same material.

Where Should the Literature Review Go?

In most journal articles, a short literature review sits inside or immediately after the introduction, before the methods section. In theses and dissertations, the literature review commonly forms its own chapter, placed after a shorter introductory chapter that states the research problem and objectives.

Some fields use a hybrid structure: a brief introduction paragraph, a longer literature review section, and a closing paragraph that restates the research question in light of the reviewed gap. Following the target publication’s or institution’s required structure matters more than following a single fixed convention.

How Long Should Each Section Be?

Length depends heavily on document type. A journal article introduction is typically 400 to 1,000 words, or roughly 5% to 10% of the total word count, while an embedded literature review within that introduction might add another 300 to 1,000 words. A standalone literature review chapter in a thesis or dissertation is far longer.

A simple planning approach allocates 1 paragraph per major theme in the literature review and 1 paragraph per major idea in the introduction. An introduction commonly uses 4 to 6 paragraphs, while a full literature review chapter can use 15 paragraphs or more, depending on how many themes must be covered.

Suggested Word Count by Document Type

Document type	Introduction length	Literature review length
Journal article	400-1,000 words	500-1,500 words
Conference paper	200-500 words	200-600 words
Undergraduate thesis	800-1,500 words	2,000-4,000 words
Doctoral dissertation	1,500-3,000 words	6,000-12,000 words

Common Mistakes to Avoid

• Summarizing studies 1 by 1 in the literature review instead of synthesizing them by theme.
• Placing the thesis statement inside the literature review instead of the introduction.
• Writing an introduction so detailed that it duplicates the literature review’s citations.
• Ending the literature review without a clear statement of the research gap.
• Citing sources without evaluating their methods, sample size, or limitations.
• Ignoring the target journal’s or institution’s required heading structure.
• Using outdated sources when more recent, relevant studies are available.

Tips for Combining Introduction and Literature Review Cleanly

When a journal requires a single combined section, draft the literature review material first as a standalone block organized by theme, then draft the introduction material separately, and merge them only at the end. This order keeps the critical analysis and the study’s own argument distinct even after merging, since overlapping citations are easier to trim when both parts already exist in full.

A second useful practice is to read only the closing paragraph of the combined section on its own. If it clearly states the research gap and how the current study addresses it, the merge has worked. If it still reads like a list of other studies, more synthesis and trimming is needed before submission.

Quick Checklist Before Submission

• Does the introduction clearly state the research problem and objectives?
• Does the literature review synthesize sources by theme rather than list them individually?
• Is the thesis statement present only in the introduction?
• Does the literature review end with a clearly stated research gap?
• Are recent, relevant sources included alongside foundational studies?
• Does the paper follow the target journal’s or institution’s required heading structure?

Frequently Asked Questions

Can the introduction and literature review be combined into 1 section?

Yes, many journal articles combine them under a single ‘Introduction’ heading, with a short literature review woven into the middle paragraphs before the research question and objectives are stated.

What is the difference between a literature review and a background section?

A background gives brief context in a few paragraphs, while a literature review is longer, more critical, and organized by theme, method, or debate rather than simple chronology or summary.

How many sources should a literature review cite?

The number varies by document type, but a journal article literature review often cites 15 to 40 sources, while a dissertation chapter can cite 100 or more, depending on the field and topic breadth.

How do I organize a literature review by theme instead of by study?

Group sources under 3 to 6 recurring themes or variables, then discuss what multiple studies say about each theme together, rather than giving each study its own paragraph in publication order.

Should the research question appear in the introduction or the literature review?

The research question belongs in the introduction, since the literature review’s role is to establish what is known and identify the gap, not to state what the current study will investigate.

How long should a literature review be in a doctoral dissertation?

Most doctoral dissertation literature review chapters run 6,000 to 12,000 words, though this varies widely by field, methodology, and how much prior research exists on the topic.

Is it acceptable to skip a separate literature review section?

Short conference papers and technical reports sometimes fold a brief literature review into 1 or 2 introduction paragraphs, but most journal articles and all theses expect a more developed, separate review.

What order should introduction and literature review follow in a thesis?

Most theses place a short introductory chapter first, stating the problem and objectives, followed by a full literature review chapter that ends by identifying the gap the study addresses.