Proofreading
Proofreading is reading a proof copy of text for the purpose of detecting errors. A proof copy is traditionally a version of a manuscript that has been typeset after copy editing has been performed.The line between copy editing and proofreading is narrow. Often, proof manuscripts contain typographical errors introduced during typesetting by the typesetter hitting incorrect keys (hence the word "typo" to refer to misplaced or incorrect characters). Earlier, when handwritten originals were common, it was often easier for a copy editor to review and mark up a manuscript after it had been typeset and the proof copy produced. Today, proofreading usually refers to reviewing any text, hardcopy or electronic copy (on a computer), and checking for any kind of errors.
See also: copy editing, typo fairies