Proofreading is the last stage in the editorial process before publication, and the corrections need to be clearly visible to the client.
I can proofread your document in Microsoft Word with Track Changes and return it to you in Word. If you prefer, I can annotate it with Xodo which saves the Word document as a PDF. I can annotate from there and return it to you in that form. Or if you submit a PDF to me rather than a Word document, I can use Xodo from the outset.
The types of corrections that I check for when proofreading a document are typographical errors, spelling, double words, punctuation, grammar, and formatting. Spelling & Grammar check in Word and proofreading apps don't catch everything, and good proofreaders don't use them. I guarantee that I don't rely on these programs to do my work. I use stylebooks and my own skill and experience to proofread.
Here is an example of the way my proofreading will appear:
Turnaround time is generally in two to six days depending on the size and complexity of the document. Shorter turnaround times are available if necessary.