What is the sentence fragment, run-on sentence and compound sentences?

So, basically, a sentence is a group of words that conveys something and then there are four types of sentences – declarative sentence, interrogative sentence, imperative sentence, and exclamatory sentence. The English language has a whole different area to study its sentences but in this article, we will learn that – What are the sentence fragment, run-on sentences, and compound sentences play a really important role in written English and must be corrected and proofread.