Good day. Here’s a little lesson which I hope you’ll find useful.
Consider three sentences:
The poet Angela Smith (who had travelled from the Shetlands) said the book festival was a huge success.
The poet Angela Smith, who had travelled from the Shetlands, said the book festival was a huge success.
The poet Angela Smith – who had travelled from the Shetlands – said the book festival was a huge success.
What is the difference between the three? It boils down to the level of importance of the additional information in the middle of the sentence.
We get that Angela Smith said the book festival was a success. That she travelled from Scotland is unimportant in the first sentence, neither unimportant or especially important in the second, and important in the third.
Use brackets when the information is an ‘aside’, of minor relevance, non-essential to the reader, and not referred to again later in the piece of writing.
Use commas when the information is of very roughly equal priority to other facts in the article, and is something you’d like your reader to note and know.
Use dashes (not hyphens, by the way) when you want to emphasise the information, for some reason. In the third case, the writer might be trying to convey the sense that the book festival was so highly regarded, so worthwhile, that somebody made the effort to travel from a remote corner of the country to attend. Alternatively, it may be intended to reflect the dedication of the poet to the festival circuit and to her fans.
(I don’t always practise what I preach, and sometimes chuck a large portion of text between dashes when I have an unwieldy and long sentence, just to make it more digestible to the reader, even when it isn’t really worth emphasising. You can probably find examples on the blog. I don’t recommend you copy me.)
Note that in these situations, you need an ‘opening’ comma, bracket or dash, and a ‘closing’ one too. Too many new writers make the mistake of putting one in, usually the first, and forgetting the other. You should be able to lift out the two punctuation marks and the content they enclose and leave a sentence which still makes grammatical sense, and is punctuated correctly:
The poet Angela Smith said the book festival was a huge success.
I’ve covered this before, with respect to brackets, here.
Note, while I’m here, that unless you have previously made reference to a poet, and are now revealing the poet’s name, using commas, like this, is best avoided:
The poet, Angela Smith, said the book festival was a huge success.
This is because there are many poets in the world, and you are referring to a particular one – the one who said the festival was a success. Treating her name as additional and, by implication, optional information is inappropriate, as it is clearly important for the reader to know which of the world’s many poets paid the festival this compliment.
When you are talking about an individual in a unique role, commas are fine:
The Poet Laureate, Carol Ann Duffy, said the book festival was a huge success.
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