The apostrophe (' or ’) character is a punctuation mark, and sometimes a diacritical mark, in languages that use the Latin alphabet and some other alphabets. In English it is used for several purposes: The marking of the omission of one or more letters (as in the contraction of do not to don't). The marking of possessive case of nouns (as in the eagle's feathers, or in one month's time). The marking of plurals of individual characters (e.g. p's and q's). The word apostrophe comes ultimately from Greek ἡ ἀπόστροφος [προσῳδία] (hē apóstrophos [prosōidía], '[the accent of] turning away or elision'), through Latin and French. According to Unicode, the apostrophe is the same character as the closing single quotation mark, although the semantics of this character are "context-dependent". (When it functions as a closing quotation mark, it is always paired with an opening quotation mark.) Other substitutes such as ´ (acute) and ‘ (open single quotation mark) are common due to ambiguous treatment of the apostrophe in early digital typesetting (as explained below). In informal contexts, the typewriter apostrophe is commonly substituted for any of a variety of similar marks and their formal purposes.