In simple language can someone please some explain apostrophes to me?

[Crusoe]

I really want to improve my spelling and grammar but confess to being very confused about the use of apostrophes.
I understand they are used to indicate missing letters e,g, can't, it's etc but really can't get my head around the rules about plurals and possession. The more I try and read the more confused I get.
Can anyone please try and explain things for my simple brain.
Thanks in advance ...

They are never used for plurals (except traditionally by greengrocers).

They are used for possessions e.g. Mary's house, Saturn's rings, the dog's tail.

Note however that there is no apostrophe is the possessive "its". So it's "The Sun has got its [not it's] hat on, hip hip hip hooray!".

"It's" with an apostrophe is short for "it is".

Hi Crusoe. I have thought of a few random examples, hope they are useful.

Yes, as you say the apostrophe is used to replace a missing letter such as it's (short for it is)
Regarding possession, I could write for example " the dog's bone." If I was referring to the dog as it, rather than he or she, the rule is a bit confusing. The correct version is "its bone" i.e. no apostrophe.
Who/whose/who's can also be confusing.
If I want to shorten "who is there?" it should read "who's there"
However if I want to ask which person an item belongs to is should be "whose coat is this?"

Anotherr though re plurals. If there are several dogs (for example) all with bones, we would write "the dogs' bones"

sorry for typo, on this topic of all places! My first two words should read "Another thought".

On the subject of greengrocers, if there are potatoes for sale, it is incorrect to put "potato's".
Same rule for tomatoes.

Ah thanks everyone what you have written does kind of help and I think I fully get the It's / Its / It is thing.

It is the possessive thing that gets me. Are the following right?
The boy's book (where there is one boy and one book)
The boys' books (where there is more than one boy and they all have one book each)
so where would you put the apostrophe where you have lots of boys and they all have lots of books each?
Sorry I really do tie myself up in knots with apostrophes.
Thanks C

Crusoe Yes that's all correct. It would still be "the boys' books" if they had lots each. You would just have to say something explicit if you wanted to point that out.

Just to add, "it's" can also mean "it has", as in "it's been a while".

Also:

The children's books.

But with words like people and children and women you don't do this:

womens' childrens' peoples' books

even though there are several women/children/people. You write:

children's women's people's

The reason for this is that the word itself already denotes a multiple, unlike boy girl dog etc.

The logic for there being no apostrophe in 'its' for example in:

'the dog chewed its bone'

is the same as the logic for

'the dog chewed his/her bone.' We don't need an apostrophe there either, obviously.

Can I hijack and ask what you do when the word already ends in an s?

Is it James' book or James's book?

My surname ends in s and it always confuses me!

To help with where to put the apostrophe when indicating ownership ask the question who is the owner of the book/car/house (etc)? Generally the apostrophe follows the response to this question.
E.g. In the examples given you would get the boy (boy's) the boys (boys')

You would also correctly get the women's, the children's and the people's.

Both are correct. there is a school of thought that it is too clumsy to write two esses together and so many people write James' book. Although no-one really says James' book, do they? They say James's book.

Jesus is a good example. Because of the two esses already in Jesus it really is clumsy to say 'in Jesus's name' so we tend to knock of the last s.

But it is not incorrect, technically, should you wish to say 'Jesus's name'.

Another example of this slight oddity is:

Clarke the family butcher. It is fine to say 'I am going to Clark's'

and yet take Boots the Chemist. We don't say we are going to Boots's - although technically we could. But it just sounds wrong. Because Boots is already a plural of a noun. Even though in the case of Mr Boots it is not a plural of a noun, but a singular proper noun.

haha - I should have said in Mr Boots' (or Mr Boots's) case!

Oh, no I shouldn't! I misremembered the order of my own sentence.

You could also have the boys' books where several books belong to the group of boys but it's not necessarily where each boy owns at least one book.

What about in house names?

We've just discovered that our little house has a grand name - St Georges Villa - but wondered why it doesn't have an apostrophe. Can anyone enlighten me? Thanks.

There bnt it gets complicated. Is it the Villa that belongs to St George??? There again - surely there is only one St George. Hmmm..... Don't even get me on St John Ambulence!!

Yes Mspontipine, St John(s) Ambulence is the same situation. I just don't know - it's beyond me. :-)

Boots (the chemist) should properly be Boot's. It refers to the Boot family who were the original owners. It is probably, however, a good deal easier not to use the apostrophe in the company name and logos.

ummmm.......ambulance?

Were they the Boot family? I thought their name was Boots.

Thought I'd just check, and my memory is correct. They were the Boot family.
Corporate web page history bit

How funny. They were always referred to as 'Boots the Chemist' and even if it were Boot's the Chemit that doesn't make grammatical sense.

Why I give a toss I really don't know.