Copyediting is the editorial stage everyone is familiar with. At this stage, the focus is at sentence level and word level. A copyeditor checks for correct grammar and spelling, clarity, flow, punctuation, consistency, formatting, paragraph and section breaks, word choice, minor fact checking . . . copyediting gets into the nitty-gritty of a manuscript.
My copyedits are thorough but not judgmental. A completed copyedit can discourage any writer; all you see is the markup. All you see are the errors. All the feelings you had in school when the teacher handed back your paper covered in red pen marks come flooding back. I try to alleviate those feelings by pointing out positives—a nice turn of phrase, for example. Comments are written to provide constructive feedback.