Clauses

What Is a Clause?

A clause is a group of words that contains a subject and a verb. Clauses are the building blocks of sentences. Understanding clauses helps you write more varied, sophisticated sentences and avoid errors like run-ons and fragments.

Key Terms

Term	Definition	Example
Subject	Who or what the clause is about	The dog barked.
Predicate	The verb and what follows it	The dog barked loudly.
Independent clause	A complete thought; can stand alone	She laughed.
Dependent clause	An incomplete thought; cannot stand alone	Because she was happy
Subordinating conjunction	Word that introduces a dependent clause	because, although, when, if
Relative pronoun	Introduces a relative clause	who, which, that

Independent Clauses

An independent clause (also called a main clause) expresses a complete thought and can stand alone as a sentence.

• The sun set over the mountains.
• She finished her homework.
• The team won the championship.

Each of these has a subject and a verb and makes complete sense on its own.

Dependent Clauses

A dependent clause (also called a subordinate clause) has a subject and verb but does not express a complete thought. It depends on an independent clause to make sense.

• Because she was tired → incomplete (because what?)
• When the storm arrived → incomplete (what happened?)
• Although he practised every day → incomplete

Dependent clauses are introduced by subordinating conjunctions such as: because, although, when, if, since, after, before, unless, while, until.

Types of Dependent Clauses

Adverbial Clauses

Tell us when, where, why, or how something happened.

• She left before the show ended.
• If you practise daily, you will improve.

Noun Clauses

Function as a noun (subject, object, or complement).

• What she said surprised everyone. (subject)
• I know that he is honest. (object)

Relative Clauses

Describe or give more information about a noun. Introduced by who, which, that, whose, whom.

• The girl who sits next to me plays violin.
• The book that I borrowed was excellent.

Defining vs non-defining relative clauses:

• Defining (no commas): The man who called left a message. (tells us which man)
• Non-defining (with commas): My brother, who lives in Dublin, is a teacher. (extra information)

Sentence Types Using Clauses

Sentence Type	Structure	Example
Simple	1 independent clause	She sings.
Compound	2+ independent clauses joined by and/but/or	She sings and he plays guitar.
Complex	1 independent + 1+ dependent clause	She sings because she loves music.
Compound-complex	2+ independent + 1+ dependent	She sings, he plays guitar, and they both love music.

Worked Examples

Identifying clauses:

"Although the weather was cold, the children played outside."

• Although the weather was cold = dependent clause (adverbial)
• the children played outside = independent clause

"The scientist who discovered penicillin changed medicine forever."

• The scientist ... changed medicine forever = independent clause
• who discovered penicillin = relative clause (defining)

Common Mistakes

• Sentence fragments: Writing a dependent clause alone as a sentence. "Because I was late." — this needs an independent clause.
• Comma splice: Joining two independent clauses with only a comma: "I was tired, I went to bed" — use and, a semicolon, or a full stop.
• Forgetting commas with non-defining relative clauses: "My dog who is very old sleeps all day" should have commas around "who is very old".

Tips and Tricks

• To check if a clause is independent, read it alone. Does it make a complete, sensible statement? If yes, it is independent.
• Dependent clauses often begin with because, although, when, if, since, after, before, unless — look for these signal words.
• Vary your sentence types to make writing more engaging: mix simple, compound, and complex sentences.
• Relative clauses are a great way to add detail without starting a new sentence: instead of "She won a prize. The prize was gold." write "She won a prize that was gold."