Grammar Girl has debunked these grammar rules, saying, “Almost everyone believes at least one of these myths.”
1. A run-on sentence is a really long sentence. Wrong. When you squish together two independent clauses, without a conjunction or punctuation, it’s a run-on sentence. Example: “I am short he is tall.”
2. “Irregardless” is not a word. Wrong. It’s a nonstandard word that you shouldn’t use if you want to be taken seriously. It is, however, in the dictionary.
3. There is only one way to write the possessive form of a word ending in “s.” Wrong. Whether you write Kansas’ or Kansas’s is a style choice.
4. You use “a” before words that start with consonants and “an” before words that start with vowels. Wrong. Use “an” before words that start with vowel sounds. Example: “an MBA.”
5. You shouldn’t split infinitives. Nearly all grammarians agree that it’s OK to boldly do so.