When dealing with parenthetical elements, subordinate clauses within sentences or embedded relative clauses, bracketing commas e.c.t.

What are the key differences in comparison to one another. For instance do parenthetical parts of a sentence have to be isolated out with brackets or is optional to just use commas. Or can you isolate subordinate clauses with brackets for emphasis instead of commas.

  • etc., not e.c.t (it is from a Latin phrase et cetera – James K Apr 10 '18 at 16:49
  • Please show evidence of prior research effort. As this question stands it is quite broad. Have you consulted one of the English grammar websites and not understood something? – James K Apr 10 '18 at 16:52
  • Brackets generally indicate supplied editorial material, such as interpolated or substituted text or inline references. You should not use them interchangeably with commas. – Robusto Apr 10 '18 at 16:52
  • By "brackets", do you mean [], {}, or ()? – Nathan Tuggy Apr 10 '18 at 16:57

There are roughly three ways of introducing parathetical elements into written English.

My hovercraft, not my aeroplane, is full of eels!

My hovercraft (not my aeroplane) is full of eels!

My hovercraft—not my aeroplane—is full of eels!

Using brackets () (also called parentheses) suggests to the reader that the part in brackets may be skipped. It is purely additional to the main meaning.

Using commas, like this, interupts the flow less. The reader shouldn't skip the part in commas.

Dashes—I have used the longer em-dash in this example—can be used for parathetical asides. They are more dramatic than commas. Use sparingly.

Generally stick to commas if you want it to always be included. Use brackets if you are happy for your reader to skip that bit.


This question (should commas or parentheses be used for parenthetical phrases?) is about style so doesn't have a definitive answer. In general parentheses are used when the information is not directly related, or when the information can be removed entirely without affecting the meaning of the sentence.

Example style guide on using parentheses

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