Myth: It’s incorrect to start a sentence with a coordinating conjunction (and, but, or, for, nor, yet, so)
This rule is a provisional one, meant to help beginning writers to see the differences between oral and written communication.
Whereas in speech we very often use conjunctions, especially “and” and “but,” in text a writer’s overuse of conjunctions at the beginnings of sentences makes for repetitive and sloppy writing. To combat this stylistic problem, people who teach beginning writers sometimes ban the use of any coordinating conjunction at the beginning of a sentence.
But such an all-out ban is misguided. In fact, plenty of good writers begin their sentences with coordinating conjunctions once in a while.
Importantly, the decision to begin with a coordinating conjunction should be made with care (as with all decisions in writing), but since it can add desirable emphasis to a sentence, it should not be ruled out. And remember, even if this kind of overuse is annoying, it’s never the cause of a grammatical error.
This article is part of Writing myths: The reasons we get bad advice.