Parentheses ( ( )parentheses )

Parentheses are used for enclosing words, phrases, or clauses which might not be grammatically related to the rest of the sentence. This may include comments, examples, appositives See the glossary definition, numbers or acronyms See the glossary definition . Dashes or commas can often serve the same purpose.

1. Appositives

   • The Centers for Disease Control and Prevention (opening parenthesisCDCacronym for Centers for Disease Control and Prevention)closing parenthesis has called insufficient sleep an epidemic.
   • The hammerhead species that branched off the earliest is the winghead shark (opening parenthesisE. blochiiscientific species name (genus + epithet))closing parenthesis, which has one of the widest heads.
   • In insects, these are found only in the scales of weevils, longhorn beetles, butterflies and moths, where they can form intricate arrays of chitin (opening parenthesisthe material that makes up the bulk of the exoskeleton of insectsappositive noun phrase explaining what chitin is)closing parenthesis and air.
   
   

2. Other Examples

   • These are animals or other organisms that live on (opening parenthesisectoparasitesorganisms that live on another species are called ectoparasites)closing parenthesis or in (opening parenthesisendoparasitesorganisms that live in another species are called endoparasites)closing parenthesis another species.
   • Since the 1960s we have known that new ocean crust is being created almost continuously along giant rifts (opening parenthesiscalled mid-ocean ridgesan ed-clause postmodifying 'rifts')closing parenthesis.
   • At the bottom of the plates, around 60 miles (opening parenthesis100 kilometersan approximate conversion from 60 miles)closing parenthesis deep, the temperature is about 2,400 degrees Fahrenheit (opening parenthesis1,300 degrees Celsiusan approximate conversion from 2,400 degrees Fahrenheit)closing parenthesis.
   
   

Test your understanding of apostrophe and parentheses punctuation with the Apostrophe - Parentheses Punctuation Quiz.