What Is a Compound Sentence?

 Understanding how sentences are built is a fundamental skill in writing and communication. One important sentence structure you should know is the compound sentence. In this article, we’ll explore what a compound sentence is, how it’s constructed, why it’s useful, and how to use it effectively to make your writing clear and engaging.

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What Is a Compound Sentence?

A compound sentence is a sentence made up of two or more independent clauses joined together. Each clause in a compound sentence can stand alone as a complete sentence because it has both a subject and a verb and expresses a complete thought.

Key Terms:

• Independent clause: A group of words with a subject and verb that can stand alone as a sentence.

• Compound sentence: Two or more independent clauses joined together.

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How Are Compound Sentences Formed?

The most common way to form a compound sentence is by connecting two independent clauses using a coordinating conjunction or a semicolon.

Coordinating Conjunctions

There are seven coordinating conjunctions in English, often remembered by the acronym FANBOYS:

• For

• And

• Nor

• But

• Or

• Yet

• So

Each of these can join two independent clauses.

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Example Using a Coordinating Conjunction

• I wanted to go for a walk, but it started to rain.

Here, “I wanted to go for a walk” is an independent clause, and “it started to rain” is another independent clause. They are joined by but, a coordinating conjunction, with a comma before it.

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Using a Semicolon

You can also join two related independent clauses using a semicolon without a conjunction.

• I wanted to go for a walk; it started to rain.

The semicolon signals a close connection between the two ideas.

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Why Use Compound Sentences?

Compound sentences serve several important purposes in writing:

1. Show Relationship Between Ideas

Using compound sentences helps show how ideas relate to each other—whether they are contrasting, adding information, showing cause and effect, or presenting alternatives.

• Contrast: She likes coffee, but he prefers tea.

• Addition: I finished my homework, and I cleaned my room.

• Cause and Effect: He was tired, so he went to bed early.

2. Make Writing Flow Smoothly

By connecting ideas in one sentence, your writing sounds less choppy and more fluid, improving readability.

3. Add Variety to Sentence Structure

Using only simple sentences can make your writing feel repetitive or monotonous. Compound sentences add variety and interest.

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How to Punctuate Compound Sentences Correctly

Proper punctuation is important when writing compound sentences.

With Coordinating Conjunctions

When joining two independent clauses with a coordinating conjunction, place a comma before the conjunction.

• Correct: The sun was shining, and the birds were singing.

• Incorrect: The sun was shining and the birds were singing.

With Semicolons

When using a semicolon, no conjunction is needed, and the semicolon itself replaces the comma and conjunction.

• Correct: She loves hiking; he prefers cycling.

• Incorrect: She loves hiking,; he prefers cycling.

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Common Mistakes With Compound Sentences

1. Run-On Sentences

A run-on sentence occurs when two independent clauses are joined without any punctuation or conjunction.

• Incorrect: I went to the store I bought some milk.

• Correct: I went to the store, and I bought some milk.

2. Comma Splices

A comma splice is when two independent clauses are joined only with a comma, which is incorrect punctuation.

• Incorrect: He was late, he missed the meeting.

• Correct: He was late, so he missed the meeting.

• Or: He was late; he missed the meeting.

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Examples of Compound Sentences

Here are several examples showing different coordinating conjunctions and semicolon use:

• I wanted to call her, but I lost her number.

• We can go to the beach, or we can stay home.

• He didn’t study, yet he passed the exam.

• The movie was long, so we took a break.

• She likes jazz; he prefers classical music.

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When to Use Compound Sentences

Compound sentences are especially useful when:

• You want to link related ideas clearly.

• You want to avoid too many short, simple sentences.

• You want to emphasize the relationship between two thoughts.

• You want to create rhythm and flow in your writing.

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Summary: What You Should Remember About Compound Sentences

Aspect	Explanation
What it is	Two or more independent clauses joined
How to join clauses	With coordinating conjunction + comma or semicolon
Coordinating conjunctions	For, And, Nor, But, Or, Yet, So (FANBOYS)
Purpose	Show relationship, improve flow, add variety
Common errors	Run-on sentences, comma splices

Conclusion

Mastering compound sentences will greatly improve your writing. They allow you to connect ideas clearly, vary your sentence structure, and write with greater sophistication. Always remember to punctuate them correctly, and use coordinating conjunctions or semicolons to join your independent clauses.