A conjunction is a word that joins words, phrases or clauses.

e.g., but, and, because, although, since, unless, or, nor, yet for, so, while,where, etc.

A conjunction can also be a group of words known as compound conjunction, e.g., as long as, as far as, as well as, in order to, even if, so that, etc.

There are three types of conjunctions:

  1. Coordinating Conjunction
  2. Subordinating Conjunction
  3. Correlative Conjunction

A coordinating conjunction joins words, phrases or clauses of similar grammatical structure. The coordinating conjunction is also called a coordinator.

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

It joins the following.

Word + Word
Phrase + Phrase
Clause + Clause

Read the following examples where the blue parts are words, phrases and clauses joined together by coordinating conjunctions (e.g., but, and, or, because) shown in red color.  

Examples.

• He closed the door and the window. (two words).
• She showed us her dog and cat. (two words)
• He broke his glass and cup. (two words).
• Would you like to have some tea or coffee? (two words).
• She is interested in reading stories and watching movies. (two phrases).
• You may meet me at my home or at my office. (two phrases).
• They usually play games in the street or in the garden. (two phrases).
• I waited for him, but he did not come. (two clauses).
• She requested him for help, but he did not help her. (two clauses).
• He always sings songs because he wants to become a singer.  (two clauses).

It can be seen in the above examples, the words, phrases and clauses joined together by coordinating conjunctions are of similar grammatical structure.

Before learning the subordinating conjunction, it is important to understand what is main clause or a subordinate clause. A clause is a group of words having a subject and an object, e.g., he laughed. There are two types of clauses:1) main clause, and 2) subordinate clause. See the following example.

• I saw a man who was laughing.

In the above sentence, the first clause ‘I saw a man’ is the main clause whereas the second clause ‘who was laughing’ is the subordinate clause. A main clause (e.g., I saw a man) can stand alone as a sentence because it gives a complete meaning. On the other hand, a subordinate clause (e.g., who was laughing) cannot stand alone as a sentence because it does not give a complete meaning. A subordinate is dependent on the main clause to give a complete meaning or make a complete sense. Therefore, the subordinate clause is also known as dependent clause. It is called a subordinate clause because it has a subordinate role in relation to the main clause in a sentence which is that it provides more information regarding the main clause.

  A subordinating conjunction is a word that joins a subordinate clause and a main clause.

For instance, in the above sentence, the word ‘who’ is a subordinating conjunction. A subordinate clause starts with the subordinating conjunction. A subordinate clause generally comes after a main clause in a sentence. However, a sentence can also start with a subordinate clause followed by a main clause.

• Main clause + Subordinate clause
• Subordinate clause + Main clause

Irrespective of the place of the subordinate clause within a sentence, the subordinate clause always starts with a subordinating conjunction. The subordinate conjunction itself is generally seen as a part of the subordinate clause. See the following examples where the blue part is a main clause, and the red part is a subordinate clause. The underlined word is a subordinating conjunction.

Examples.

• We met the boy who had won the competition.
• I saw the man who had helped me last year.
• This is the car which I like the most.
• You can live a happy life provided that you think optimistically.
• We saw a car which was badly damaged in an accident.
• I will not tell him the secret even if he insists a lot.
• He gifted me a book which helped me in preparation for my exam.
• I will give you my camera whenever you need it.
• Although it is raining, it is too hot today.
• As far as I know, he is a nice person.
• If you avoid sugary foods, you can easily lose weight.
• Since most of the members are absent, we should cancel the meeting.

A correlative conjunction is a paired word. It joins words, phrases, or clauses having a reciprocal or complementary relationship.

The common correlative conjunctions are as follows:

• Either …. or
• Neither .… nor
• Whether .… or
• Both …. and
• Not only .… but also 
• As … as
• Such … that
• Rather … than

Examples. 

• He will buy either a laptop or a camera.
• She likes neither tea nor coffee.
• Both pink and blue are my favorite colors.
• Both sugary juices and fatty foods cause weight gain.
• She is interested not only in watching movies but also in listening to music.
• You will find him either in the library or in the classroom.
• I would rather eat a burger than a pizza.
• It was such a cold day that we had to turn the heater on.
• He is as intelligent as you.