Some thoughts on punctuation

One thing I often notice when proofreading, or indeed reading for leisure, is that some writers have punctuation marks they use frequently or perhaps some that they use rarely, if at all. I have noticed anecdotally on social media that many fiction authors openly love the em dash, but I have come across authors who barely use them. Likewise, some authors (and readers) love the semi-colon but others loathe it. When proofreading, I try my best to put my personal preferences to one side, as what really matters is that the text is grammatically correct.

Semi-colons should be used instead of commas when the author wishes to connect two independent clauses which do not have a conjunction, e.g. "I have a meeting with my bank manager; it starts at noon." They can also be used to separate items in a complex list, such as when the items contain commas, e.g. "I've lived in Swindon, Wiltshire; Coventry, Warwickshire; and Buxton, Derbyshire." Semi-colons should also be placed before conjunctive adverbs, e.g. "I love cycling; however, it is dangerous in London." Finally, they can replace conjunctions, e.g. "I walked into the library; I renewed my books."

Em dashes can be used to highlight additional information, much like brackets, e.g. "the town of Wilmslow - known for its wealthy locals - lay just south of Manchester." They can also be used to indicate interruptions, e.g. "I was planning a trip to Spain - but then I became ill." Another usage is to introduce an explanatory clause, e.g. "Djokovic arrived at Wimbledon with one thing in his mind - lifting the trophy." They can also introduce lists, and - more interestingly - can sometimes be used in place of semi-colons, e.g. "He had all his desires - money, status and a beautiful wife."

A side note about em dashes is that there is some debate about whether they should have spaces on either side. Standard practice in modern writing seems to be for no spaces to be used, but some styles such as AP do require spaces. There is therefore a degree of author licence here.

If you are a writer of any kind, I would encourage some use of semi-colons and/or em dashes - providing of course that they are used correctly and not over-used to an unnecessary degree. In an academic essay, appropriate use of semi-colons adds guile to a piece of writing. In fiction, em dashes can be a great way of adding a sense of urgency or drama to a short story or novel.