Punctuation: Different Punctuation marks: Apostrophes

An apostrophe is primarily used as part of a word with the letter s to show possession or to indicate that letters in a contraction have been omitted.

POSSESSIVES (indicating ownership):

1. In English, the apostrophe (') plus s forms the possessive singular of all nouns and the possessive plural of all nouns not ending in s.
singular: man's role John's party
plural: men's role children's playground


2. Use the apostrophe alone to form the plural nouns ending in s.
dogs' fur Aguilars' house*
boys' pants Joneses' cars

*NOTE: If an "s" is added to a surname to refer to the whole family's belongings or as a greeting card signature, do not include an apostrophe:

ex., The Aguilars (or Smiths or Joneses) live there. Season's Greetings, The Highsmiths

3. To form the possessive singular of indefinite pronouns, use the apostrophe plus s.
everyone's success one's leg
somebody's house anybody's home

NOTE:

• Use the -s possessive with nouns referring to persons and living things. Use an "of" phrase for the possessive of nouns referring to inanimate objects. Awkward: The chair's back was broken. Improved: The back of the chair was broken.

• Nouns or pronouns which modify gerunds are usually possessive. Mary's singing irritated Tom.John's laughter attracted attention.

• When forming the possessive, avoid unpronounceable duplication of sound. Awkward: conscience's sake, Awkward: conscience's sake
  

Improved: conscience' sake

Awkward: Claudins's feast
Improved: Claudins' feast


CONTRACTIONS:

Contractions are two words condensed into one by replacing a letter or group of letters with an apostrophe. (Remember, in formal/academic writing contractions should not be used.)