An Apostrophe Does not a Plural Make

Plurals are formed by adding s or es to the root word. That's it. Nothing else. This is a simple rule but apparently it's a difficult one for some people to learn. When I see an apostrophe s instead of plural in a book, I think it's a typo, but when I see several, I figure the author or editor doesn't know how to form a plural. When I see misused apostrophes, I usually see many other grammatical