Conjunctions in English are used to connect words, phrases, or clauses in a sentence. There are three main types: coordinating (e.g., and, but, or – "She likes tea and coffee."), subordinating (e.g., because, although, while – "I stayed home because it was raining."), and correlative (e.g., either...or, neither...nor – "Either you study hard, or you fail."). Using conjunctions correctly helps create smooth and logical sentences.