Apostrophe
The apostrophe (’, ') is a punctuation mark and sometimes a diacritical mark in languages that use the Latin alphabet and some other writing systems. In English, the apostrophe is used for two 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") It is also used in a few exceptional cases for the marking of plurals, e.g., "p's and q's" or Oakland A's.