Preposition vs Conjunction: Differences, Rules & 40+ Examples

Have you ever wondered why before, after, and since sometimes introduce a short phrase and sometimes introduce a whole clause?

Look at these sentences:

We finished our homework before dinner.
We finished our homework before dinner started.

Both are correct. However, in traditional school grammar, before is a preposition in the first sentence and a subordinating conjunction in the second.

The difference comes from the words that follow it.

Understanding preposition vs. conjunction helps you write clearer sentences, connect ideas naturally, and avoid common mistakes with words like because, because of, although, despite, during, and while.

In this guide, you will learn what prepositions and conjunctions are, how they differ, and how to identify them in real sentences. You will also find 40 numbered examples, comparison tables, easy grammar rules, common mistakes, practice questions, and FAQs.

Quick Answer: Preposition vs. Conjunction

A preposition typically introduces a phrase that expresses a relationship involving time, place, direction, cause, or another meaning. A conjunction connects words, phrases, or clauses.

Compare:

The bag is under the chair. — Under is a preposition.
I bought tea and coffee. — And is a coordinating conjunction.
We stayed home because it rained. — Because is a subordinating conjunction.
We left after lunch. — After is traditionally a preposition.
We left after lunch ended. — After is traditionally a subordinating conjunction.

Some modern grammar frameworks classify words like after as prepositions in both constructions.

Easy memory trick: Prepositions express relationships; conjunctions connect grammatical units.

TL;DR: Preposition vs. Conjunction

Prepositions often introduce phrases describing time, place, direction, cause, or purpose.
Conjunctions join words, phrases, or clauses.
Common prepositions include in, on, at, under, between, beside, and during.
Common conjunctions include and, but, or, because, although, if, and unless.
In traditional grammar, before, after, since, and until may be prepositions or subordinating conjunctions.
The best way to identify them is to examine their function and sentence structure.

Feature	Preposition	Conjunction
Main job	Expresses a relationship	Connects grammatical units
Common words	In, on, under, during	And, but, because, although
Typical structure	Preposition + noun phrase	Conjunction + connected unit or clause
Time example	Before lunch	Before lunch began
Cause example	Because of traffic	Because traffic was heavy
Main question	What relationship does it express?	What does it connect or introduce?

Preposition vs. Conjunction: Quick Difference

The simplest way to understand preposition vs. conjunction is to look at the structure of the sentence.

A preposition commonly introduces a noun phrase.

For example:

“She arrived after the meeting.”

Here, after introduces the noun phrase the meeting.

A subordinating conjunction introduces a dependent clause in traditional grammar.

“She arrived after the meeting ended.”

Here, after introduces the clause the meeting ended.

Quick Comparison

Preposition use	Conjunction use
Before dinner	Before dinner started
After school	After school ended
Since Monday	Since the course began
Until midnight	Until the clock struck midnight

Three Easy Identification Steps

Step 1: Find the word you want to identify.

Step 2: Check what follows it or what it connects.

Step 3: Decide whether it introduces a relational phrase, joins equal grammatical units, or introduces a dependent clause.

For example:

“She studied in the library because she had a test.”

In introduces the noun phrase the library. Because introduces the dependent clause she had a test.

Important: These tests describe traditional school grammar. Some modern grammars use different word-class labels for certain clause-introducing words.

What Is a Preposition?

A preposition is a word that commonly introduces a phrase expressing a relationship between its complement and another part of the sentence.

Prepositions can show place, time, direction, movement, cause, purpose, means, and other relationships.

Prepositions of Place

These describe where something is located.

Examples:

The cat is under the bed.
The picture hangs above the sofa.
She stood beside her friend.

Prepositions of Time

These describe when something happens.

Examples:

The meeting starts at nine.
We arrived before lunch.
She worked during the weekend.

Prepositions of Direction

These describe movement or direction.

Examples:

He walked into the room.
They traveled toward the city.
The children ran across the field.

Prepositions of Cause and Purpose

Some prepositions express reasons or purposes.

Examples:

The flight was delayed because of fog.
She studied for the exam.
The event was canceled due to bad weather.

Common Prepositions Chart

Preposition	Example	Meaning
In	In the box	Inside
On	On the table	Surface or position
At	At noon	Specific time
Under	Under the chair	Lower position
Between	Between two houses	Position
Before	Before dinner	Earlier time
After	After lunch	Later time
Into	Into the room	Movement inward
During	During class	Time period
Because of	Because of rain	Reason

Key point: Prepositions do more than describe physical locations. They can also express time, reason, manner, comparison, and other relationships.

What Is a Conjunction?

A conjunction is a word or construction that connects grammatical units or introduces a dependent clause.

Conjunctions help writers combine information and explain relationships between ideas.

Traditional grammar recognizes three major groups: coordinating conjunctions, subordinating conjunctions, and correlative conjunctions.

Coordinating Conjunctions

Coordinating conjunctions connect words, phrases, or clauses of equal grammatical status.

A popular memory trick is FANBOYS:

For — reason
And — addition
Nor — negative alternative
But — contrast
Or — choice
Yet — contrast
So — result

Examples:

“She likes tea and coffee.”

“He was tired, but he continued.”

Subordinating Conjunctions

These introduce dependent clauses in traditional grammar.

Common examples include because, although, if, when, while, and unless.

“I stayed home because I felt sick.”

“Although it was raining, we went outside.”

Correlative Conjunctions

Correlative conjunctions work in pairs.

Common examples include both … and, either … or, neither … nor, and not only … but also.

“Both Sarah and Emma attended.”

“Either call me or send a message.”

Conjunction Comparison Chart

Type	Examples	Function
Coordinating	And, but, or	Joins equal units
Subordinating	Because, although, if	Introduces dependent clauses
Correlative	Either … or	Connects paired alternatives

Remember: Conjunctions make it easier to combine ideas without writing many short, disconnected sentences.

Preposition vs. Conjunction Comparison Chart

Prepositions and conjunctions sometimes express similar meanings, but their grammatical roles differ.

Main Differences

Question	Preposition	Conjunction
What does it do?	Introduces a relational phrase	Connects units or introduces a clause
What commonly follows it?	A noun phrase	A word, phrase, or clause
Can it express time?	Yes	Yes
Can it express cause?	Yes	Yes
Can it join equal units?	Not normally	Yes
Example	During the meeting	While the meeting continued
Example	Because of the rain	Because it rained

Preposition Example

“The children played after school.”

After school tells us when the children played.

Conjunction Example

“The children played after school ended.”

In traditional grammar, after introduces the dependent clause school ended.

Both in One Sentence

“We waited at the station until the train arrived.”

Here, at is a preposition introducing the station. In traditional grammar, until is a subordinating conjunction introducing the train arrived.

Why This Matters

Choosing the correct structure makes your writing more natural.

Correct:

“We stayed home because of the storm.”

Also correct:

“We stayed home because the storm was dangerous.”

Writing tip: Learn the patterns that follow each word instead of memorizing definitions alone.

How to Identify a Preposition in a Sentence

You can often identify a preposition by examining the phrase it introduces.

Test 1: Look for a Noun Phrase

“The keys are on the desk.”

On introduces the desk.

Test 2: Check the Relationship

“She arrived before noon.”

Before expresses a time relationship.

Test 3: Look for Direction

“He walked through the tunnel.”

Through describes the route of movement.

Test 4: Look for Cause

“The match was canceled because of the storm.”

Because of introduces a noun phrase expressing the cause.

Test 5: Identify the Entire Prepositional Phrase

“She sat beside her brother.”

The full prepositional phrase is beside her brother.

Can a Preposition Appear at the End?

Yes.

“Who are you talking to?”

The preposition to appears at the end, while its understood complement is represented by who earlier in the question.

Ending a sentence with a preposition is not automatically incorrect in English.

Key takeaway: A preposition’s function matters more than its position.

How to Identify a Conjunction in a Sentence

Conjunctions connect grammatical units or introduce dependent clauses.

Test 1: Look for Connected Words

“I bought apples and oranges.”

And connects two nouns.

Test 2: Look for Connected Independent Clauses

“She was tired, but she continued working.”

But connects two independent clauses.

Test 3: Look for a Reason Clause

“I stayed home because I was sick.”

Because introduces a dependent clause explaining the reason.

Test 4: Look for a Condition

“If you practice, you will improve.”

If introduces a conditional clause.

Test 5: Look for Paired Connectors

“Either Sarah or Emma will present.”

Either … or connects two alternatives.

Independent vs. Dependent Clauses

An independent clause can stand alone as a complete sentence.

“I stayed home.”

A dependent clause generally cannot stand alone as a complete sentence.

“Because it was raining.”

Together:

“I stayed home because it was raining.”

Quick Identification Chart

Sentence	Word	Traditional classification
She arrived after lunch.	After	Preposition
She arrived after lunch ended.	After	Subordinating conjunction
Tea and coffee are available.	And	Coordinating conjunction
We stayed home because it rained.	Because	Subordinating conjunction

Important: Not every conjunction introduces a clause. Coordinating conjunctions can also connect individual words and phrases.

20 Examples of Prepositions in Sentences

These examples show how prepositions express place, time, movement, cause, and other relationships.

Prepositions of Place

The keys are on the table.
The cat slept under the chair.
She stood beside her friend.
The ball rolled behind the sofa.
The store is between two buildings.

Prepositions of Time

The meeting begins at noon.
We arrived before dinner.
She called after lunch.
He has lived here since 2020.
They talked during the break.

Prepositions of Direction and Movement

She walked into the room.
The children ran across the field.
He drove toward the airport.
We traveled through the mountains.
The bird flew over the fence.

Other Common Prepositions

She bought flowers for her mother.
The match was canceled because of rain.
He succeeded through hard work.
The book was written by a historian.
Everyone attended except Daniel.

Remember: Prepositions can describe where, when, how, why, or in what direction something happens.

20 Examples of Conjunctions in Sentences

These examples show coordinating, subordinating, and correlative conjunctions.

Coordinating Conjunctions

I bought apples and oranges.
She was tired, but she kept working.
Would you like tea or coffee?
He was hungry, so he made dinner.
The task was difficult, yet she finished it.

Subordinating Conjunctions

I stayed home because I was sick.
Although it was raining, we went outside.
If you practice, you will improve.
Call me when you arrive.
She listened while he explained the plan.

Time and Condition Conjunctions

We left after the movie ended.
Finish your homework before you watch TV.
Wait here until the bus arrives.
Since you are ready, we can begin.
You can join us unless you have other plans.

Correlative Conjunctions

Both Sarah and Emma attended.
Either call me or send a text.
Neither the manager nor the assistant was available.
She is not only talented but also hardworking.
I don’t know whether he will stay or leave.

Key point: Conjunctions help express addition, contrast, choice, cause, time, and condition.

Types of Prepositions in English Grammar

Prepositions can be grouped according to the relationships they express.

Prepositions of Place

These describe location.

Examples include in, on, under, beside, and between.

“The bag is under the desk.”

Prepositions of Time

These describe when something happens.

Examples include at, on, in, before, after, and during.

“The meeting starts at nine.”

Prepositions of Direction

These describe movement or direction.

Examples include to, into, toward, through, and across.

“She walked toward the station.”

Prepositions of Cause

These express reasons.

Examples include because of, due to, and owing to.

“The flight was delayed because of fog.”

Prepositions of Manner or Means

These explain how something happens.

Examples include by, with, and through.

“She opened the package with scissors.”

Simple vs. Complex Prepositions

A simple preposition usually consists of one word.

Examples: in, on, at, under.

A complex preposition contains more than one word.

Examples: because of, in front of, according to.

Type	Examples	Sentence
Place	Under, beside	Under the table
Time	Before, during	Before dinner
Direction	Into, toward	Into the room
Cause	Because of	Because of rain
Means	By, with	With a key
Complex	In front of	In front of the house

Grammar tip: These categories describe meanings, so one preposition can belong to more than one group depending on the sentence.

Types of Conjunctions in English Grammar

Traditional grammar recognizes three major types of conjunctions.

Coordinating Conjunctions

These connect words, phrases, or clauses of equal grammatical status.

Examples: and, but, or, nor, yet, so, for.

“She enjoys reading and writing.”

Subordinating Conjunctions

These introduce dependent clauses.

Examples: because, although, if, unless, when, while.

“Although she was tired, she finished the project.”

Correlative Conjunctions

These work in pairs.

Examples:

Both … and
Either … or
Neither … nor
Not only … but also

“Both the teacher and the students were ready.”

Conjunction Types Comparison

Type	Examples	Function
Coordinating	And, but, or	Connects equal units
Subordinating	Because, although, if	Introduces dependent clauses
Correlative	Either … or	Connects paired alternatives

Are However and Therefore Conjunctions?

However, therefore, and moreover are usually classified as conjunctive adverbs or linking adverbs rather than coordinating conjunctions.

Correct:

“She was tired; however, she continued.”

Also correct:

“She was tired. However, she continued.”

A comma alone is not enough to join two independent clauses with however.

Comma Rules for Conjunctions

Rule 1: Use a comma before a coordinating conjunction that joins two independent clauses.

“She studied hard, and she passed the test.”

Rule 2: Do not automatically use a comma when joining two words.

“I bought apples and oranges.”

Rule 3: Use a comma after an introductory dependent clause.

“Although it was raining, we went outside.”

Rule 4: A dependent clause following the main clause often needs no comma.

Word	Preposition use	Conjunction use
Before	Before the meeting	Before the meeting began
After	After lunch	After lunch ended
Since	Since Monday	Since the course began
Until	Until sunset	Until the sun set

Why Do Grammar Books Sometimes Disagree?

Traditional school grammar often classifies words like before, after, since, and until according to the structure they introduce.

Some modern grammar frameworks classify them as prepositions in both uses.

For example:

“After lunch” contains a noun phrase complement.

“After lunch ended” contains a clause complement.

Under the modern analysis, after remains a preposition in both sentences.

Important: Both sentences are correct English. The disagreement concerns grammatical classification, not whether the sentences are acceptable.

Preposition vs. Conjunction: Clauses and Phrases

Understanding phrases and clauses makes the traditional distinction easier.

What Is a Phrase?

A phrase is a word or group of words functioning as a grammatical unit.

A prepositional phrase commonly contains a preposition and its complement.

Example:

“After the meeting“

What Is a Clause?

A clause contains a predicate and, in ordinary finite clauses, a subject.

Example:

“After the meeting ended“

Here, the meeting is the subject and ended is the verb.

Phrase vs. Clause Comparison

Phrase	Clause
Before dinner	Before dinner started
After school	After school ended
Since Monday	Since the course began
Until sunset	Until the sun set

Because vs. Because Of

Use because before a finite clause.

“She stayed home because she was sick.”

Use because of before a noun phrase.

“She stayed home because of her illness.”

During vs. While

Use during before a noun phrase.

“She called during the meeting.”

Use while before a clause.

“She called while the meeting was taking place.”

Although vs. Despite

Use although before a clause.

“Although she was tired, she continued.”

Use despite before a noun phrase or suitable -ing construction.

“Despite her tiredness, she continued.”

“Despite feeling tired, she continued.”

Key takeaway: Recognizing noun phrases and clauses helps you choose the right word and structure.

Common Preposition vs. Conjunction Mistakes

Writers sometimes confuse prepositions and conjunctions because certain expressions have similar meanings.

Common Mistakes Chart

Incorrect or awkward	Correct	Explanation
Because the rain, we stayed home.	Because of the rain, we stayed home.	Use because of before a noun phrase
Because of it rained, we stayed home.	Because it rained, we stayed home.	Use because before a clause
Despite it was cold, we went out.	Although it was cold, we went out.	Use although before a clause
Although the rain, we played.	Despite the rain, we played.	Use despite before a noun phrase
During I was studying, she called.	While I was studying, she called.	Use while before a clause
I was tired, however I continued.	I was tired; however, I continued.	Avoid a comma splice

Mistake 1: Because vs. Because Of

Incorrect:

“We stayed home because the rain.”

Correct:

“We stayed home because of the rain.”

Also correct:

“We stayed home because it rained.”

Mistake 2: Although vs. Despite

Incorrect:

“Despite it was cold, we went outside.”

Correct:

“Although it was cold, we went outside.”

Also correct:

“Despite the cold weather, we went outside.”

Mistake 3: During vs. While

Incorrect:

“During I was studying, she called.”

Correct:

“While I was studying, she called.”

Also correct:

“She called during my study session.”

Mistake 4: Joining Independent Clauses Incorrectly

Incorrect:

“I was tired, I continued working.”

Correct:

“I was tired, but I continued working.”

Also correct:

“I was tired; however, I continued working.”

Mistake 5: Adding Unnecessary Commas

Usually unnecessary:

“I bought apples, and oranges.”

Better:

“I bought apples and oranges.”

When and joins two simple nouns, a comma is generally unnecessary.

Easy Memory Tricks

Preposition = Relationship
Conjunction = Connection
Because + clause: Because it rained.
Because of + noun phrase: Because of rain.
During + noun phrase: During class.
While + clause: While class continued.
Although + clause: Although it was cold.
Despite + noun phrase: Despite the cold weather.

Best tip: Check what follows the word and how it functions in the sentence.

Preposition vs. Conjunction Practice Quiz

Choose the best answer using traditional school grammar.

Questions

1. Which word is a preposition in “The cat slept under the bed”?

A. Slept
B. Under
C. Cat
D. The

2. Which word is a coordinating conjunction in “She was tired, but she continued”?

A. Tired
B. Continued
C. But
D. She

3. Which sentence uses because correctly?

A. We stayed home because the rain.
B. We stayed home because it rained.
C. We stayed home because of it rained.
D. We stayed home because raining.

4. In “We arrived before sunset,” how is before traditionally classified?

A. Conjunction
B. Preposition
C. Pronoun
D. Noun

5. Which sentence uses during correctly?

A. During I studied, she called.
B. During she arrived, we left.
C. She called during the meeting.
D. During it rained, we waited.

6. Which sentence correctly joins two independent clauses?

A. She was tired, she continued.
B. She was tired, but she continued.
C. She was tired, however she continued.
D. She was tired because of she continued.

Answers and Explanations

1. B — Under. It introduces the noun phrase the bed and shows location.

2. C — But. It connects two independent clauses and shows contrast.

3. B — We stayed home because it rained. Because introduces a clause.

4. B — Preposition. In traditional grammar, before introduces the noun sunset.

5. C — She called during the meeting. During introduces a noun phrase.

6. B — She was tired, but she continued. The comma and coordinating conjunction correctly join the clauses.

Answer Key: 1-B | 2-C | 3-B | 4-B | 5-C | 6-B

Frequently Asked Questions

What is the main difference between a preposition and a conjunction?

A preposition typically introduces a phrase showing a relationship, such as under the table. A conjunction connects grammatical units, as in tea and coffee or because it rained. Some words have different classifications depending on the grammar framework.

Can a word be both a preposition and a conjunction?

Yes, in traditional grammar. Words such as before, after, since, and until are commonly called prepositions before noun phrases and subordinating conjunctions before clauses. Some modern grammars analyze them as prepositions in both uses.

Is because a preposition or conjunction?

Because is traditionally a subordinating conjunction when it introduces a clause, as in “because it rained.” Because of is a complex preposition, as in “because of the rain.” Informal uses such as “because science” also exist.

Is before a preposition or conjunction?

In traditional grammar, before is a preposition in “before dinner” and a subordinating conjunction in “before dinner started.” Modern grammatical analyses may classify both uses as prepositional.

What are five examples of prepositions?

Five common prepositions are in, on, at, under, and between. They can show relationships involving location, time, or position.

What are five examples of conjunctions?

Five common conjunctions are and, but, or, because, and although. They connect words, phrases, or clauses and express relationships such as addition, contrast, choice, and reason.

What is the difference between during and while?

During normally introduces a noun phrase, as in “during class.” While introduces a clause, as in “while the teacher was speaking.” Both can express time, but their grammatical structures differ.

How can I identify prepositions and conjunctions easily?

Look at the structure and function. A preposition often introduces a noun phrase that expresses a relationship. A conjunction connects grammatical units or introduces a dependent clause. Be careful with words such as before, after, since, and until, which have different analyses across grammar frameworks.

Conclusion and References

Understanding preposition vs. conjunction helps you build clearer and more accurate English sentences.

A preposition typically introduces a phrase showing a relationship involving place, time, direction, cause, or another meaning.

A conjunction connects words, phrases, or clauses and helps show relationships such as addition, contrast, reason, condition, and time.

The most useful beginner rule is to examine the structure following the word.

Compare:

Before dinner — Traditionally a prepositional phrase.
Before dinner started — Traditionally a conjunction introducing a clause.

Remember that modern grammatical frameworks sometimes classify these structures differently. The important skill is understanding how the word works in context.

Practice with real sentences, check whether the following words form a noun phrase or clause, and pay attention to common pairs such as because/because of, although/despite, and while/during.

Final memory rule: Prepositions express relationships; conjunctions connect grammatical units.