What is a clause?

A clause is a part of a sentence. There are two main types: independent (main clauses), dependent (subordinate clauses).

Independent Clauses

An independent clause is a complete sentence; it contains a subject and verb and expresses a complete thought in both context and meaning.

For example: The door opened.

Independent clauses can be joined by a coordinating conjunction to form complex or compound sentences.










For example: Take two independent clauses and join them together with the conjunction and: " The door opened." "The man walked in." = The door opened and the man walked in.

Dependent Clauses

A dependent (subordinate) clause is part of a sentence; it contains a subject and verb but does not express a complete thought. They can make sense on their own, but, they are dependent on the rest of the sentence for context and meaning. They are usually joined to an independent clause to form a complex sentence.

Dependent clauses often begin with a a subordinating conjunction or relative pronoun (see below) that makes the clause unable to stand alone.






even if

even though


in order that


provided that

rather than


so that














Relative Pronouns









For example:

The door opened because the man pushed it.

Dependent clauses can be nominal, adverbial or adjectival.

A nominal clause (noun clause) functions like a noun or noun phrase. It is a group of words containing a subject and a finite verb of its own and contains one of the following: that | if | whether

For example:

  • I wondered whether the homework was necessary.

Noun clauses answer questions like "who(m)?" or "what?"

An adverbial clause (adverb clause) is a word or expression in the sentence that functions as an adverb; that is, it tells you something about how the action in the verb was done. An adverbial clause is separated from the other clauses by any of the following subordinating conjunctions: after | although | as | because | before | if | since | that | though | till | unless | until | when | where | while

For example:

  • They will visit you before they go to the airport.

Adverbial clauses can also be placed before the main clause without changing the meaning.

For example:

  • Before they go to the airport, they will visit you.

!Note - When an adverb clause introduces the sentence (as this one does), it is set off with a comma.

Adverb clauses answer questions like "when?", "where?", "why?"

An adjectival clause (adjective clause or relative clause) does the work of an adjective and describes a noun, it's usually introduced by a relative pronoun: who | whom | whose | that | which

For example:

  • I went to the show that was very popular.

This kind of clause is used to provide extra information about the noun it follows. This can be to define something (a defining clause), or provide unnecessary, but interesting, added information (a non-defining clause).

For example:

  • The car that is parked in front of the gates will be towed away. (Defining relative clause.)

Information contained in the defining relative clause is absolutely essential in order for us to be able to identify the car in question.

  • My dog, who is grey and white, chased the postman. ( Non-defining relative clause)

A non-defining relative clause is separated from the rest of the sentence by commas. If you take away the non-defining clause the basic meaning of the sentence remains intact.

For example:

  • My dog chased the postman.

Adjective clauses answer questions like "which?" or "what kind of?"


An adjective clause functions as an adjective (modifies a noun or pronoun); an adverb clause functions as an adverb (describes a verb, adjective or other adverb); a noun clause is used as a noun (subject of a verb, direct object, indirect object, predicate nominative or object of the preposition).

!Note - The difference between a clause and a phrase is that a phrase does not contain a finite verb.

Relative Clauses

A relative clause follows the noun it modifies. It is generally indicated by a relative pronoun at the start of the clause, although sometimes you can tell simply by word order. The choice of relative pronoun, or choice to omit one, can be affected by the following:-

Human or Non-human?

We make a distinction between an antecedent that is a human — who(m) — and an antecedent which is a non-human — which.

Who(m) is used when the antecedent is a person.
That is used to refer to either a person or thing.
Which is used to refer to anything exept a person.

  • I met a man and a woman yesterday. The woman, who had long blonde hair, was very pretty.
  • The man she was with, was the man that / who won the race.
  • The race was the one that I lost.
  • The man, to whom the winnings were given, was with the woman who was very pretty.

!Note - Whom is not used much in spoken English.

Restrictive or Non-restrictive?

Restrictive relative clauses are sometimes called defining relative clauses, or identifying relative clauses. Similarly, non-restrictive relative clauses are called non-defining or non-identifying relative clauses.

In English a non-restrictive relative clause is preceded by a pause in speech or a comma in writing, unlike a restrictive clause.

For example:-

The builder, who erects very fine houses, will make a large profit.
This example, with commas, contains a non-restrictive relative clause. It refers to a specific builder, and assumes we know which builder is intended. It tells us firstly about his houses, then about his profits.

The builder who erects very fine houses will make a large profit.
This second example uses a restrictive relative clause. Without the commas, the sentence states that any builder who builds such houses will make a profit.

Restrictive Non-restrictive
Human Nonhuman Human Nonhuman
Subject who, that which, that who which
Object who, whom, that, Ø which, that, Ø who, whom which
After preposition whom which whom which


whose, of whom whose, of which whose, of whom whose, of which