Apostrophe

1. Use an apostrophe in possessive forms:

• the ball of the boy » the boy's ball
• Tara's sister
• my friend's mother
• New York's nightmare scenario
• the moon's phases

2. Use an apostrophe in contracted forms (the apostrophe shows that letters have been left out):

• cannot » can't
• they have » they've
• I would (or I had) » I'd
• it is (or it has) » it's
• who is » who's

Certain words are sometimes written with an apostrophe (to show that they are really a shortened form of the original, longer word):

• influenza » 'flu (or flu)
• telephone » 'phone (or phone)

Some people use an apostrophe when the first two figures of a year are left out:

• 1948 » '48

3. You can use an apostrophe to show the plural of letters and numbers:

• You should dot your i's and cross your t's.
• Do you like music from the 1950's?

You can use an apostrophe to show a plural form for words that are not normally plural:

• Your plan is good, even if there are lots of but's in it.

Possessive pronouns or determiners (except one's) do not use apostrophes. Do not confuse them with contractions. The following are typical mistakes:   Wrong Right It's value is Its value is It's going to rain Who's are these? Whose are these? Who's coming? These are your's These are yours exception » One's self-esteem