Common text editing marks include a caret for inserting text or punctuation, or underlining text to change the style to italic or bold. Because text editing marks are usually handwritten, it is best to look at a visual list online, such as Merriam-Webster's dictionary.
Text editing marks are often referred to as proofreaders' marks and are more commonly used when proofs are in paper form. They are marked within the text with a corresponding mark in the margin to alert the reader to the correction. Today, the majority of proofreading is done digitally through tracked changes in Microsoft Word or with Adobe Acrobat markup tools.