I am still studying English skills. I wondered whether the books by known authors who write English have been corrected with the help of proofreaders, right? Or sometimes not?
i am looking forward to hear from you. thank you
Very few (if any) reputable publishers will publish a book before it has been edited - in consultation with the author. If the language is too mangled, most publishers/agents will insist on proofreading and correction (at the author's expense) before they will even look at it. The final version will be carefully proofread before the book is published.
Context is always important; labelling is rarely important.