The purpose of a proofreading service is quite simple: to remove typos and grammatical errors while adding a little bit of native speaker expertise. Here we usually mean so-called monolingual proofreading, which means that the proofreader has no insight into the source content. By contrast, revision - often also referred to as editing - means bilingual proofreading, i.e. the proofreader compares the translated content with the source document. The second language proofreader is therefore familiar with both languages and is perfectly capable of making content and stylistic corrections.