Always trouble with little nasty commas?

They are small and more than often overlooked during inspired writing, but nevertheless important. And tricky. Punctuation marks like commas, dots or semicolons can drive to madness when checking spelling errors. Because we never really feel sure about the rules that apply to them. And, to be honest, who cares in daily life about the comma rules?

Punctuation errors are nasty only in some cases, when they change the meaning of a phrase or lead to misunderstandings. And because they are very often overlooked when proofreading a text.

What do the rules tell about the use of commas?

Obviously we could consider answering first the question about who decided about these rules, but as we did not found any definite answer to that, we just stick on what we have found on standard sources like the oxford dictionary of grammar and others.

Starting to read about commas we stumbled upon the grammarbook and stopped counting by the 21st rule. Enough is enough.
We had the intention of presenting here is a brief overview of English punctuation rules regarding the use of commas.

But when I went to authoritative sources to download something like “10 comprehensive rules about the use of commas” I understood that despite their pragmatism in general, English punctuation rules are as tedious and pedantic as the German rules, which until now I thought were the masters of complex language rules.

To make things complicated, there are rules about what you should do and rules about what you should not do. Some rules have their own dos and don’ts. They are quite specific, but it would be too easy to make it simple, right?


  • Use a pair of commas to surround a non-defining clause, where only ‘which’ or ‘who’ can be used.
  • The surrounded clause has to add descriptive information which can be removed without losing the meaning of the sentence.
  • Use commas to surround a non-defining word or phrase. The phrase adds information but could be omitted without changing the sense of the sentence and use a single comma if the non-defining word/phrase is at the start of the sentence
  • Use a comma after an introductory adverb, adverbial phrase or subordinate clause; or use a pair of commas surrounding it if it is in the middle of a sentence
  • Use a comma after an introductory adverb, adverbial phrase or subordinate clause; or use a pair of commas surrounding it if it is in the middle of a sentence
  • Use a comma between multiple qualitative adjectives (those which can be used in the comparative/superlative or modified with ‘very’, ‘quite’ etc.)
  • Use a comma between items in a list
  • Note that there is generally no comma between the penultimate item and ‘and’/‘or’, unless required to prevent ambiguity – this is sometimes referred to as the ‘Oxford comma’.

  • Use commas to surround a defining clause where ‘that’ or ‘which’ are used and where the clause cannot be removed without losing the meaning of the sentence.
  • Do not use a comma where a non-defining clause is used at the start of a sentence
  • Do not use a comma to join two main clauses, or those linked by adverbs or adverbial phrases such as ‘nevertheless’, ‘therefore’ etc. Either use a semicolon or add a coordinating conjunction (eg and, but, so)
  • Do not use a comma after a time-based adverbial phrase
  • Do not use a comma between multiple classifying adjectives: absolutes which either are or are not, such as ‘unique’, ‘English’, ‘black’ etc. (although note that stylistically these can be modified)
  • Do not use a comma between classifying and qualitative adjectives
  • Do not use a comma between classifying and qualitative adjectives

It would be madness to remember every rule consciously when writing an article. We instinctively “know the rules” and after the first creative rush we use to step back and take a look. Or we just run a spell checker over the text and start correcting whatever error comes up.
It makes sense just to keep the spirit of the rules: Sentences must be clear in their intention and in what they reference to. Keeping this simple principle in mind makes things easier.
There are however commas that are vital for the meaning of a sentence and others that are optional.

Finally, 17 rules …

for all those who like being ruled and have good memory.

So here go some basic rules to keep in mind, as we can’t help ourselves to make a list of rules. But I can assure you, I prefer to use a dozen checkers than to rely on my mnemonic capabilities for grammar rules.

  1. Commas are used between two main sentences if these are closely related in their significance. Some say commas should be put even if the two sentences are connected with ‘and’ or ‘but’, others would see this as an error. Partial sentences get separated by a comma unless they are connected via an ‘and’ or a ‘but’.
  2. Secondary sentences are separated by a comma only if they appear before the main phrase and mark the beginning of a sentence.
  3. In phrases beginning with ‘if-clauses’ the comma separates the ‘if’-condition from the ‘then’-consequence.
  4. Commas mark the beginning of an indirect speech when the introductory explanation appears first. If the explanation of who is speaking appears after the speech, the comma goes before the quotation mark. If the direct speech ends with a questions mark or an exclamation mark we don’t use a final comma.
  5. Clauses that are not part of the main sentence are surrounded by commas. Also relative clauses with ‘who’ and ‘which’ are surrounded by commas if their significance is not vital for the meaning of a sentence. (We saw this above)
  6. Usually there is a comma after initial clauses with an infinitive or prepositional phrase as well as after an initial participative sentence.
  7. When two or more adjectives with equal rank appear in a consecutive order, they are separated by a comma.
  8. Contrasts get separated by a comma too, unless they are connected with ‘and’ or ‘but’, where they are optional.
  9. Some adverbs require a comma after them. After ‘so’, ‘then’ and ‘yet’ it is optional.
  10. Lists also get separated by commas, being optional before ‘and’, unless they are part of a given phrase like ‘fish and chips’ or ‘ham and eggs’.
  11. The thousands in numbers are separated by commas. Decimals are separated by dots. This way you must write 10,000,000 million dollars but $9.99.
  12. Writing dates we use commas to separate the year if there are more then two date characters, so it will be May 6, 2014 but May 2014.
  13. The beginning of direct speech is marked with a comma, but after the initial greeting it is not mandatory.
  14. Geographical information like city, state are separated by a comma, like in Dublin, Ireland or Idaho, US
  15. Addresses need a comma to separate each element, like in 32nd Street, Manhattan, New York.
  16. And, of course, before a courtesy ‘please’ you will add a comma, please.
  17. After denying or confirming a question we need to add a comma, like in ‘No, I don’t want to!’ or ‘You’ll never understand this, do you?’

Clean your brain-RAM and use a spell checker you can configure!
After all this, who would NOT run every spell checker available?
As always, we made a little comparison and test with the spell checker for Word in Office 2010 and our own service here at To be sure to get an official rule set, we just took the examples of the Oxford Styleguide to compare both outcomes for British English.
There are 34 sentences with examples for the use of commas. Five of them are incorrect.
We just pasted the sentences in Word 2010.
Result: No errors found.
We did the same with Online-Spellcheck: Some other errors found that may be false positives, but no punctuation errors.
A professional and experienced copywriter perhaps would not need any spell and grammar checker to make a standard correct use of comma rules. But not so experienced or just stressed writers will type first and proofread later.
With an integrated spell checker it would be difficult to know what the grammar checker had overlooked for a less savvy user. The same problems would arise over and over.
With a configurable online checker a user could define the rules once and have to forever. Uploading the final draft to a personal customization of Online Spellcheck would find the rules that Word misses.
The advantage using a web based tool is that these rules are maintained by a community that has committed to enhance and refine the rule sets. You can easily add your own rules to your online spell checker.