2026.07.22
2026.07.31

What Are Conjunctions? Types, Rules, and Examples

Key Takeaways

Conjunctions connect words, phrases, and clauses. English has 4 main types: coordinating, subordinating, correlative, and conjunctive adverbs.
Correct conjunction use prevents comma splices, run-on sentences, and fragments, which are common issues in academic and professional writing.
Researchers conjunctions to signal cause, contrast, condition, and sequence.
Non-native speakers learn conjunctions faster by grouping them by function, such as cause or contrast, rather than memorizing an alphabetical list.

Table of Contents

Glossary of Key Terms

Term	Definition
Conjunction	A word that connects words, phrases, or clauses and shows the relationship between them.
Coordinating conjunction	1 of 7 words (for, and, nor, but, or, yet, so) that join 2 grammatically equal elements.
Subordinating conjunction	A word such as because or although that connects a dependent clause to an independent clause.
Correlative conjunction	A paired conjunction, such as either/or or both/and, used to connect balanced sentence parts.
Conjunctive adverb	A transitional word, such as however or therefore, that links 2 independent clauses with a semicolon.
Independent clause	A group of words with a subject and verb that can stand alone as a complete sentence.
Dependent clause	A group of words with a subject and verb that cannot stand alone and relies on another clause.
Comma splice	An error in which 2 independent clauses are joined only by a comma, with no conjunction.
Run-on sentence	2 or more independent clauses joined without correct punctuation or a connecting word.
Transition word	A word or phrase that guides the reader from 1 idea, sentence, or paragraph to the next.

What Is a Conjunction?

A conjunction is a word that joins words, phrases, or clauses within a sentence. Conjunctions show how ideas relate to each other, whether through addition, contrast, cause, condition, or time. Without conjunctions, writing would consist of short, disconnected sentences that fail to show logical relationships between ideas.

English organizes conjunctions into 4 main categories: coordinating conjunctions, subordinating conjunctions, correlative conjunctions, and conjunctive adverbs. Each category follows a different grammar pattern and a different punctuation rule, covered in detail in the sections below.

Why Do Conjunctions Matter in Academic and Professional Writing?

Conjunctions matter because they signal the logical relationships a reader needs to follow an argument. Weak or missing conjunctions can blur cause-and-effect claims, hide contrasts between findings, or make a dissertation chapter read as a list of disconnected facts rather than a coherent argument.

They help writers avoid short, choppy, disconnected sentences.
They clarify whether 2 ideas support each other, contradict each other, or occur in sequence.
They reduce ambiguity in complex sentences that contain multiple clauses.
They improve the flow of transitions between paragraphs and sections of a document.
They help distinguish correlation from causation, a distinction that matters in quantitative research.

What Are the Main Types of Conjunctions?

English conjunctions fall into 4 main categories, each with its own grammatical role and punctuation pattern. The sections below cover coordinating, subordinating, and correlative conjunctions, plus conjunctive adverbs, which function as adverbs but are often grouped with conjunctions because of their connecting role.

Coordinating Conjunctions

Coordinating conjunctions join 2 grammatically equal elements, such as 2 independent clauses, 2 nouns, or 2 phrases. English has exactly 7 coordinating conjunctions, remembered with the acronym FANBOYS: for, and, nor, but, or, yet, and so.

For: The team postponed the launch, for the data set was incomplete.
And: The survey included 500 participants and 12 follow-up questions.
Nor: The results were not significant, nor were they consistent across the 3 trials.
But: Revenue increased in Q1, but operating margins declined.
Or: Researchers could apply a t-test or a Mann-Whitney U test.
Yet: The sample size was small, yet the effect size was large.
So: The p-value exceeded 0.05, so the researchers retained the null hypothesis.

Rule: place a comma before a coordinating conjunction when it joins 2 independent clauses. Do not add a comma when the same word joins 2 single words or 2 phrases instead of 2 full clauses.

Subordinating Conjunctions

Subordinating conjunctions connect a dependent clause to an independent clause, showing a relationship such as time, cause, condition, or contrast. Common examples include because, although, since, if, when, while, unless, and whereas.

Cause: because, since, as
Condition: if, unless, provided that
Time: when, while, before, after, until
Contrast: although, though, whereas, even though

Example: Although the trial included 3 hospital sites, researchers analyzed the data as a single cohort.

Rule: add a comma after an introductory dependent clause. When the dependent clause follows the independent clause, a comma is usually not needed.

Correlative Conjunctions

Correlative conjunctions work in pairs to connect balanced sentence elements. Common pairs include either/or, neither/nor, both/and, not only/but also, and whether/or.

Example: The study measured not only blood pressure but also heart rate variability.

Rule: keep the grammatical structure parallel on both sides of the pair. If 1 side uses a noun, the other side should also use a noun, not a verb phrase.

Conjunctive Adverbs

Conjunctive adverbs, such as however, therefore, moreover, consequently, and furthermore, connect 2 independent clauses while adding transitional meaning. Grammatically, they function as adverbs rather than true conjunctions, but writers group them with conjunctions because of their connecting role.

Example: The intervention reduced symptoms; however, the effect faded after 6 weeks.

Rule: use a semicolon before and a comma after a conjunctive adverb when it joins 2 independent clauses.

What Rules Govern Conjunction Use?

The core rule is that conjunction choice depends on what elements are being joined and what logical relationship the writer wants to show. Punctuation errors around conjunctions are among the most common grammar mistakes in academic writing.

Punctuation Rules

Use a comma before a coordinating conjunction that joins 2 independent clauses.
Do not use a comma when a coordinating conjunction joins 2 words or 2 phrases rather than 2 clauses.
Use a comma after an introductory subordinate clause that begins a sentence.
Use a semicolon, not a comma, before a conjunctive adverb that joins 2 independent clauses.
Use a comma before the final and or or in a list of 3 or more items, often called the Oxford comma, which improves clarity in academic writing.

Common Mistakes to Avoid

The table below lists frequent conjunction errors seen in research papers and dissertations, along with a corrected version of each example.

Mistake	Example	Correction
Comma splice	Sales rose, the market stayed volatile.	Sales rose, but the market stayed volatile.
Missing comma before FANBOYS	The drug reduced inflammation and patients reported fewer side effects.	The drug reduced inflammation, and patients reported fewer side effects.
Comma before a conjunctive adverb	Results improved, however, funding was cut.	Results improved; however, funding was cut.
Unparallel correlative pair	Not only the results were significant but also reliable.	The results were not only significant but also reliable.

Conjunctions Across Research Fields

Conjunctions carry specific weight in research writing because they signal the logical architecture of an argument: cause, contrast, condition, and sequence. Choosing the wrong conjunction can overstate a finding, such as implying causation when only correlation was tested. The examples below show how conjunctions function in 3 broad research areas.

Business and Social Sciences

Contrast: Consumer spending increased in urban markets, whereas rural markets showed stagnation.
Cause: Because employee turnover rose by 18%, the firm revised its retention policy.
Condition: If interest rates rise above 5%, mortgage demand is expected to fall.
Correlation caution: Sales and marketing spend increased together, but the data do not establish causation.

Biomedical Sciences

Condition: Unless contraindicated, patients received the standard dose of the medication.
Cause: Since biomarker levels were elevated, clinicians ordered additional imaging.
Contrast: The treatment group showed improvement, although 2 participants withdrew due to side effects.
Sequence: Patients fasted for 12 hours; subsequently, blood samples were collected.

Physical Sciences

Condition: If the temperature exceeds 100 degrees Celsius at standard pressure, water transitions to vapor.
Cause: Because the reaction was exothermic, the container temperature rose by 15 degrees.
Contrast: The alloy resisted corrosion, yet it showed reduced tensile strength under stress.
Sequence: The sample was cooled to -20 degrees Celsius, and then analyzed under a microscope.

How Can Non-Native English Speakers Master Conjunctions?

Non-native speakers master conjunctions faster by learning them in functional groups, such as cause, contrast, condition, and addition, rather than as 1 long alphabetical list, and by practicing with sentences from their own field of study.

Group conjunctions by function rather than memorizing them alphabetically.
Practice with sentences drawn from your own field of study, not generic textbook examples.
Watch for direct translation errors, since many languages apply different punctuation rules around conjunctions.
Read published academic texts and note how conjunctions appear at clause boundaries.
Limit sentences that begin with “and” or “but” in formal writing, though occasional use is accepted in modern style guides.
Use grammar-checking tools like Paperpal, which is trained on millions of research papers, but verify suggestions against a style guide instead of accepting every change automatically.
Keep a personal reference list of conjunctions with 1 example sentence taken from a published paper in your discipline.

Tips for Using Conjunctions in Essays, Dissertations, and Research Papers

Essays

Vary conjunctions so the essay does not repeat and or but in every sentence.
Use subordinating conjunctions to show nuanced arguments, such as combining cause and concession in 1 sentence.
Avoid opening every paragraph with a conjunctive adverb such as however.

Dissertations

Use conjunctive adverbs such as therefore and consequently to connect findings to implications in the discussion chapter.
Be precise with causal conjunctions; because implies causation, while and does not.
Keep conjunction use consistent across chapters to maintain a formal, unified academic tone.

Research Papers

In the methods section, use sequence conjunctions such as then, after, and once to clarify procedural steps.
In the results section, avoid conjunctions that imply causation unless the statistical analysis supports it.
In the discussion section, use contrast conjunctions such as although and whereas to compare findings with prior literature.

What’s a Quick Way to Reference All Conjunction Types?

The table below summarizes all 4 conjunction types, their core function, and 1 example each, useful as a quick desk reference while writing or editing a draft.

Type	Function	Example
Coordinating	Joins 2 equal words, phrases, or clauses	The lab ran 3 trials, and each trial used a new sample.
Subordinating	Connects a dependent clause to an independent clause	Because funding was limited, the study used a smaller cohort.
Correlative	Connects balanced sentence parts in pairs	The report was both concise and data-rich.
Conjunctive adverb	Links 2 independent clauses with transitional meaning	The results were promising; therefore, a follow-up study began.

Frequently Asked Questions

What is the difference between a coordinating and a subordinating conjunction?

A coordinating conjunction joins 2 equal elements, such as 2 independent clauses, while a subordinating conjunction connects a dependent clause to an independent clause. Coordinating conjunctions include and and but; subordinating conjunctions include because and although.

Do you need a comma before because?

In most cases, no. When because introduces a reason at the end of a sentence, no comma is needed. A comma is only needed if the clause is nonessential or if because begins the sentence and introduces a dependent clause.

Can you start a sentence with and or but in academic writing?

Yes, most current style guides, including APA, accept starting a sentence with “and” or “but” for emphasis or flow. It is best used sparingly in formal academic writing, since overuse can weaken a professional tone.

What are the 7 coordinating conjunctions called?

The 7 coordinating conjunctions are for, and, nor, but, or, yet, and so, remembered using the acronym FANBOYS. Each 1 joins 2 grammatically equal words, phrases, or clauses.

Is “however” a conjunction or an adverb?

“However” is a conjunctive adverb, not a true conjunction. It connects 2 independent clauses in meaning, but grammatically it functions as an adverb, so it requires a semicolon before it and a comma after it.

How do you punctuate correlative conjunctions like either or?

Correlative conjunctions such as either/or typically need no extra punctuation beyond what the surrounding sentence requires. The key rule is parallel structure: the words or phrases on both sides of the pair should match grammatically.

What is a conjunctive adverb and how is it different from a conjunction?

A conjunctive adverb, such as therefore or moreover, links ideas across 2 independent clauses but functions grammatically as an adverb. True conjunctions, by contrast, belong to their own part of speech and follow different comma or semicolon rules.

What is the most common conjunction mistake in research papers?

The most common mistake is implying causation with a conjunction such as “so” or “because” when the data only show correlation. Reviewers often flag this issue, so it is worth checking every causal conjunction against the actual statistical evidence.

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