A comma is a form of punctuation used to separate independent clauses, phrases and words in a sentence. It breaks a sentence into segments to minimize reader confusion and to maximize clarity and meaning in writing, according to Purdue University's Online Writing Lab.Continue Reading
The Online Writing Lab, or OWL, provides a detailed overview and examples of standard rules for comma usage. In English grammar appropriate comma usage includes scenarios such as indicating a pause, separating multiple words in a series, offsetting nonessential clauses and free modifiers, preceding a quotation, and separating independent clauses from coordinating conjunctions.
Commas also appear in geographical names to separate a city's name from its state or country, in dates to separate the month and day from the year, in the geographical location of street addresses, and in names and titles to separate a name from a title, such as "MD." Commas are not used to break up essential clauses in a sentence, such as clauses beginning with "that." They are not used to separate a subject from a verb or to separate compound predicate verbs or verb phrases, states the OWL.
One of the most hotly debated topics in grammar is the serial comma, which is the comma that precedes the conjunction in a list. Grammar authorities in American English such as the Associated Press Stylebook discourage consistent use because it is often superfluous. Other authorities such as the Chicago Manual of Style require its use for consistency and clarity.Learn more about Conditions & Diseases