A conjunction is a word that connects sentences, clauses and words.
Conjunctions are connectors. They connect (join) words or groups of words in a sentence.
They can join nouns to nouns, pronouns to pronouns, verbs to verbs, adjectives to adjectives, or adverbs to adverbs. This kind of pairing is what we mean by "equal rank." The words must be the same part of speech. The only exception is that nouns and pronouns can be joined, since pronouns can replace nouns. We do not connect an adjective with an adverb, for instance, because we do not use the two parts of speech in the same way.
Conjunctions are divided into three main groups:
Joins words or word groups of equal rank. E.g. and, or, either, neither, nor, yet, for, but, etc.
Maria and Jim were present yesterday.
Neither of the boys played the game.
The car keys are either in your bag or in your pocket.
Begins with a dependent clause and joins it to the rest of the sentence. E.g. after, although, as, because, before, how, if, in order that, since, so that, though, unless, until, when, where, while.
He offered me money so that I could buy the car.
She came after her dancing class.
Rohit did not look in my direction because he was angry.
Correlative Conjunction: is used in pairs.
both-and, so-that, neither-nor, either-or, whether-or, not only-but also.
Connects two sentences in an adverbial manner.
also, anyhow, besides, consequently, furthermore, however, in addition, in fact, likewise, nevertheless, otherwise, still, then, therefore, thus, etc.