CommasStay organized with collectionsSave and categorize content based on your preferences.
Page Summary
Use the serial (or Oxford) comma in a list of three or more items to avoid ambiguity.
Place a comma after introductory words and phrases, and between independent clauses joined by a coordinating conjunction.
Use a comma beforewhichin nonrestrictive clauses and after conjunctive adverbs likehoweverortherefore.
Generally avoid a comma beforebecauseunless it starts a nonrestrictive clause.
Refer to specific sections for guidance on punctuating numbers and examples.
Use commas to separate items in a series, and use commas to separate certain kinds of
clauses.
Serial commas
In a series of three or more items, use a comma before the finalandororto avoid potentially changing the meaning of the sentence. This comma is called a serial
comma or an Oxford comma.
Recommended: Locations are divided into
zones, regions, and multi-regions.
Not recommended: Locations are divided into
zones, regions and multi-regions.
Commas after introductory words and phrases
In general, place a comma after an introductory word or phrase.
Recommended: Finally, only groups that
contain parameters appear in this list.
Recommended: Based on the requirements of
your game, you can implement this method to update game information.
Commas separating two independent clauses
When a coordinating conjunction (and,but,or,nor,for,so, oryet) separates two independent
clauses, insert a comma after the first clause (before the conjunction) unless
both clauses are very short.
Recommended: The libraries make
feed creation easier, and they ensure that only valid feeds are produced.
Not recommended: The libraries make
feed creation easier and they ensure that only valid feeds are produced.
Recommended: Type your ID and clickOK.
Not recommended: Type your ID, and clickOK.
Commas separating independent from dependent clauses
When an independent clause and a dependent clause are separated by a
coordinating conjunction, insert a commaonly ifthe sentence could
be misunderstood without one.
Recommended: Direct-access flags are
plain variables and can be read directly.
Not recommended: Direct-access flags are
plain variables, and can be read directly.
Recommended: The manager acknowledged the
last team member who entered the room, and started the meeting.
Not recommended: The manager acknowledged
the last team member who entered the room and started the meeting.
Set off other kinds of clauses
It's often a good idea to set off certain kinds of clauses with a comma or
other punctuation for clarity.
A couple of specific places where commas are a good idea:
In general, put a comma before the wordwhichat the start of a
nonrestrictive clause. For more information about this topic, see this guide's section onrelative pronounsand Grammar
Girl's page onwhichversusthat.
In general, put a semicolon or a period or a dash before a conjunctive
adverb, such asotherwise,however, ortherefore, and put a comma after
the conjunctive adverb.
In general, don't use a comma before the causal conjunctionbecauseunless it starts a nonrestrictive clause. For more information,
see theChicago Manual of StyleQ&A entry onusing
commas withbecause.
Recommended
Not recommended
Name of the group, which has a maximum length of 200 characters.
Name of the group which has a maximum length of 200 characters.
The variable must have a value; otherwise, the server returns an error.
The variable must have a value otherwise the server returns an error.
You can use the same key name in multiple backend services and backend buckets, because
each set of keys is independent of the others.
You can use the same key name in multiple backend services and backend buckets because
each set of keys is independent of the others.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2025-08-05 UTC."],[],["Commas are used in series, before the final *and* or *or* (serial comma). They follow introductory words/phrases and separate independent clauses joined by coordinating conjunctions, unless very short. Commas may clarify meaning between independent and dependent clauses. Commas should be used before *which* in nonrestrictive clauses. Punctuation, like semicolons or periods and commas, is needed around conjunctive adverbs. Usually, avoid a comma before *because* in restrictive clauses.\n"]]
