Can you give me an example of when it's ok to use a comma before 'and'.

[beccahamlet]

That's it. Thanks very much.

It's called the Oxford comma, and is used break up a sentence into breath size pieces, is what is my take on it. (And I've done it here!!)

There was a selection of breakfast items on the table: cereal, yoghurt, a pot of tea, and toast.

It is an Oxford comma, though I don’t entirely agree with the definition above.

All morning the weather was awful, and then suddenly the sun came out

My friends are Tom, Dick, and Harry.

I went to the pub with my parents, Maggie Smith, and Tony Blair.

The Oxford/serial comma is for lists with ‘and’ or ‘or’, but it’s a style choice, so is neither correct nor incorrect.

@SueGeneris

There was a selection of breakfast items on the table: cereal, yoghurt, a pot of tea, and toast.

That’s precisely the example of when NOT to use it!

Whenever it helps to make the meaning of the sentence clearer

To make something clearer

"I'd like to thank my parents, the Queen and Harry Styles"

V

"I'd like to thank my parents, the Queen, and Harry Styles"

In the second example the command makes it clear that you are thanking your parents and two other people. The first might be read as if your parents are Harry Styles and The Queen.

It's exactly as @LavenderAskew describes. It's for clarification in a list. And it matters very much.

"I'm going to split the inheritance equally between Joseph, Clive, Peter and Sue."

It's not clear here if the inheritance is divided in to 3 chunks with Peter and Sue sharing a chunk.

"I'm going to split the inheritance equally between Joseph, Clive, Peter, and Sue."

Hurrah Peter and Sue now have they're own equal share of the inheritance.

I love giving punctuation advice on Mumsnet, and sometimes I even find myself doing it correctly.

I’d like to thank my parents, Bill and Gladys.
You’re thanking two people called Bill and Gladys who are your parents.

I’d like to thank my parents, Bill, and Gladys. You’re thanking four people.

Also I sometimes use it if I’m listing several departments with and in the title e.g.
I’d like to thank legal, sales, marketing, and research and development. (Where R&D is one department)

Or if I want to be clear that sales and marketing are separate departments:
I’d like to thank legal, R&D, sales, and marketing.

It could also happen if you inserted a parenthesis into a sentence and chose to use commas instead of brackets.

Jack had aimed to bake 30 cookies, and had made enough icing for 30, but a mistake with the recipe meant he ended up with just 24.

Of course you could just use brackets for clarity, but sometimes commas read better.

@Soontobe60 - I don't see why you wouldn't use a comma there:

There was a selection of breakfast items on the table: cereal, yoghurt, a pot of tea, and toast.

It makes it clear that the scope of "a pot of..." is only for the tea, so helps me as a reader see toast as a separate item.

If we had

potatoes, tomatoes, a bowl of tuna and mayonnaise

I'd read that as tuna and mayonnaise combined in a bowl, but

potatoes, tomatoes, a bowl of tuna, and mayonnaise

would suggest the mayonnaise was separate.

I think commas are definitely one area of writing where it's a matter of judgement based on what makes it clearer for the reader.

"I looked at Tom, and Tom looked at me".
"I looked at Tom and listened carefully".

Comma in first example indicates change of subject. Not universal in UK but tends to be observed in US and imposed by Microsoft grammar check.

1. Oxford comma - putting comma before "and", after last item on a list with more than two items. Occasionally aids clarity. Can look clunky on short lists, in graphics etc.

"The dresses come in three designs: brown, black and white, and grey".

Saves confusion there, but wouldn't be the only way to do that. Not compulsory.

Agree I'd use it for clarity in list ending "pot of tea, and toast". And in "breakfast options: porridge, tea and toast, cereal".

But I wouldn't have put it on the Brexit 50p coin - not needed for clarity and messes up the design.

Classic ones are:

“His funeral was attended by his ex-wives, Vic Reeves and Bob Mortimer.” Which makes it sound like Vic and Bob were his ex wives versus

“His funeral was attended by his ex-wives, Vic Reeves, and Bob Mortimer.”

I'd like to thank my parents, Madonna and Joseph Rees-Mogg.

Vs

I'd like to thank my parents, Madonna, and Joseph Rees-Mogg.

Forget pedantry, @Eechuffingnuff , I'm dying to know now the circumstances where someone would be thanking their parents, Madonna and Jacob(?) Rees-Mogg!

I like two courses for breakfast: bacon and eggs, and toast and jam.

@PlantyPotts

It's exactly as *@LavenderAskew* describes. It's for clarification in a list. And it matters very much.

"I'm going to split the inheritance equally between Joseph, Clive, Peter and Sue."

It's not clear here if the inheritance is divided in to 3 chunks with Peter and Sue sharing a chunk.

"I'm going to split the inheritance equally between Joseph, Clive, Peter, and Sue."

Hurrah Peter and Sue now have they're own equal share of the inheritance.

I think that's the best description so far.

Apart from Peter and Sue having 'they're' own share.
It's 'their' in that sentence. This is Pedants' Corner after all