Apostrophe

The apostrophe (' or ’) is a punctuation mark, and sometimes a diacritical mark, in languages that use the Latin alphabet and some other alphabets. In English, the apostrophe is used for three basic purposes:

• The marking of the omission of one or more letters, e.g. the contraction of "do not" to "don't"
• The marking of possessive case of nouns (as in "the eagle's feathers", "in one month's time", "the twins'‌ coats")
• Use as a single quotation mark

It is also used in a few distinctive cases for the marking of plurals, e.g. "p's and q's" or Oakland A's.

It is also used informally to indicate the units of foot, minutes of time, and minutes of arc, although in these uses, the prime symbol is generally preferred.

The word "apostrophe" comes ultimately from Greek ἡ ἀπόστροφος [προσῳδία] (hē apóstrophos [prosōidía], '[the accent of] turning away or elision'), through Latin and French.