Proofreading marks were, and still are, the marks that a proofreader would use to show where there were mistakes in the text that needed checking or correcting.
For each change in the text two marks were added to the page; one in the body of the text to show where the mistake was and another in the margin. The mark in the margin was specific to the error while the mark in the text was more general, often just being a caret to indicate the position of the mistake.
Symbols were used to make sure that the document remained readable, even after several people had corrected and proofread it. If each change were to be written onto the page it would soon become messy and very difficult to understand. The use of marks and symbols helped keep the page tidy and readable.
Often if further instructions were needed or a section was to be rewritten the proofreader or editor would mark the position with a letter and then write their longer comments on a separate piece of paper under the heading of that particular letter.
Most editing and proofreading is now done in word processing or editing software using features such as Track Changes in Microsoft Word or the equivalents in other programs.
However there are still situations in which you might need to know and understand proofreading symbols and marks. For example, in graphic design where text is incorporated, you might have to make changes on a printed draft, or you might get a scientific paper back from the editors of the journal and they might have used proofreaders’ marks.
I have included the proofreading marks in the following three tables for you to use as a reference, and then used a few of them in an example of a document with the marks added. But you should remember that there's a lot of variation in proofreading symbols. These marks are not universally used by all proofreaders; they're just examples of some of the marks used.
Some of the marks towards the end of the tables would not be used very often at all nowadays as much of the type setting is done electronically in software programs (they've been included anyway for completeness).
If you need help with proofreading and correcting your own work I offer a proofreading service through which I correct your writing. I check the grammar, spelling, style, sentence construction and general flow of the work. I copy edit your essays, reports or theses so that the English used is excellent.
If you'd like to ask me any questions you can visit the Excellent Proofreading and Writing Facebook page where I'd be happy to offer you any help or advice that I can.
By Jolyon Dodgson, copyright © 2011-2013
Proofreading and writing help for excellent first impressions.