Proofreading is done at the final stages of development, when a document is being sent for printing, submitted for moderation (e.g. dissertations or theses), or submitted to a publisher, competition, etc.
It is a check on the spelling, grammar, punctuation and layout. If an organisation has a house style, it also includes ensuring consistency with this style. It includes checking the formatting of tables, illustrations, references and indexes.
I proofread to BSI 2005 standard mark-up symbols, on paper, in Word or pdf.
Please contact me to discuss your requirements and for a free, no obligation quote. I also offer sample page / chapter proofs.