Apostrophe

The apostrophe has two uses. The first is to denote a missing letter or letters.

Missing letters

I'm means I am: the apostrophe denotes a missing "a". You're is short for you are. In you'd - you would - the apostrophe stands in for four letters: woul. Won't is odd as it's a contraction of will not and ought to be willn't really. It's is short for it is.

Possessive

The second use of the apostrophe is to denote a possessive. My aunt's pen means the pen possessed by my aunt. In principle, you simply add 's. But what if you have many aunts who jointly own the family pen? The rule suggests you'd write my aunts's pen, but the last s is dropped and you write my aunts' pen. So my dog's kennel implies I have one dog whereas my dogs' kennel means I have several dogs. (Note: possessive pronouns and possessive adjectives don't have apostrophes. His, hers, its, ours, yours, theirs.)

Tricky Ones

Kings Road is OK: it's a road where you'd expect to see kings; kings describes the nature of the road. By contrast, King's Road is a road that is (or was) owned by a king. Speakers Corner - a corner where you might find speakers. Though if they have pretty much taken over the place and made it their own you could make a case for Speakers' Corner. Tricky.

Plurals - NO NO NO!

It is WRONG to write apple's, tea's, etc when you simply mean many apples or teas. So it's 1960s, DVDs and CVs unless it's possessive as in 1960s' music or my DVD's cover, or a missing letter as in my CV's fantastic.

Exceptions

As always with English spelling and grammar there are exceptions and times when people won't agree what is correct. Is it Mr Jones' van or Mr Jones's van? Bridgit Jones' Diary or Bridgit Jones's Diary? We favour Jones's. But Barclays' traders. Write it like you say it? English, dontcha just love it.

Next: It's and Its

Teaching the use of the apostrophe