and, but, as etc.
John and David came here.
I reached home early but couldn't sleep.
As he is ill, he can't go to school today.
Conjunctions are of the following four types.
1. Compound Conjunctions:
Compound Conjunctions are groups of words that work as single conjunctions.
As well as, as if, as though, so that, as soon as, even if, in case etc.
He bought some fruits as well as vegetables.
He talked as if (or as though) he knew everything.
I gave him the book so that he could study for exam.
As soon as he came, it began to rain.
I shall go to the market even if it rains.
I shall tell you everything in case you meet me.
2. Correlative Conjunctions or Correlatives:
Some conjunctions are used in pairs. Such conjunctions are called correlative conjunctions or simply correlatives.
Either-or, neither-nor, both-and, not only-but also etc.
Either Karim or Rahim will come.
Neither he nor his brother is responsible.
Both he and his wife work in the same office.
He is not only a leader but also a hero in the public eye.
3. Coordinating Conjunctions:
Coordinating Conjunctions join words, phrases or clauses that are of equal rank. Equal rank means these words, phrases and clauses can express complete meaning even if they are not joined by conjunctions. And, but, therefore etc are coordinating conjunctions. I came home early. I couldn't sleep. These two sentences make complete sense even if not joined by conjunctions. When joined the two sentences will make one sentence: I came home early but couldn't sleep.
Coordinating Conjunctions are of four types:
A. Cumulative or Copulative Conjunctions:
These conjunctions simply add words, phrases or sentences but do not show options, contrasts and consequences which the other three types do.
Examples: And, both-and, as well as, not only-but also.
John and David came here.
Both he and his brother are reading now.
He as well as his brother will go.
He is not only rich but also honest.
B. Alternative or Disjunctive Conjunctions:
Such conjunctions show two possible options.
Examples: Either-or, neither-nor, or, otherwise etc.
Either he or his brother will attend the party.
Neither John nor his brother is eligible for the post.
Study hard or you will fail.
Study hard, otherwise you will fail.
C. Adversative Conjunctions:
Such conjunctions denote a contrast between two ideas.
Examples: But, yet, still, nevertheless etc.
He is poor but (or yet or still) he is honest.
He is poor, nevertheless he donated a lot.
D. Illative Conjunctions:
Such conjunctions denote a consequence.
Examples: For, therefore, so etc.
I shall not attend the class today for I am ill.
He worked hard, therefore he succeeded.
4. Subordinating Conjunctions:
Subordinating conjunctions join a subordinate clause to a principal clause. Subordinating conjunctions show time, reason, purpose, effect, comparison, condition, manner etc.
Examples: As, because, so that, lest, in order that, that, till, until, when, before, if, unless, so-that, so-as, than, as if, as though, though, although, however, whatever etc.
Wait here till or until I return. (time)
When I was singing, he was dancing. (time)
He reached home before it rained. (time)
I can't go there as or because I am ill. (reason)
He is studying hard so that or in order that he may pass the exam. (purpose)
Walk fast lest you should miss the train. (purpose)
I shall not go if it rains. (condition)
Unless you are honest, you can't enter the kingdom of God. (condition)
He is not so intelligent as you are. (comparison)
He is taller than you. (comparison)
He talks as if or as though he knew everything. (manner)
Though or although he is poor, he is honest. (concession)
However intelligent you may be, you can not solve this problem. (concession)
It has to be remembered that a conjunction can also belong to other word classes or parts of speech at times. For example: before and after can act as adverbs, conjunctions and prepositions.
He came home before it rained. (conjunction)
He came home before evening. (preposition)
I met him before. (adverb)
Moreover the same conjunction can belong to more than one category. For Example: So that is both a compound and a subordinating conjunction.