Coordinating conjunctions are the familiar two- and three-letter words that link two independent clauses and typically appear in the middle of a sentence. The acronym "fanboys" is often used to remember the list of coordinating conjunctions: "for," "and," "nor," "but," "or," "yet" and "so." The necessity of a comma varies depending on the length of the sentence and the complexity of the ideas being represented. For example, a comma can modify a run-on sentence to produce a compound sentence: "I celebrated my birthday with a party and a visit to the circus[,] but my favorite part was spending time with family." However, a writer may choose to omit the comma in a sentence where the two clauses are short and balanced. In the following example, the clarity of the sentence is preserved even without a comma: "I went to a party but didn't stay long."
Subordinating conjunctions join two independent clauses to form a sentence in which one clause becomes dependent. A subordinate, or dependent, clause relies on the independent clause to convey its meaning. The conjunction always appears at the beginning of the subordinate clause, but the clause itself can be positioned at the beginning or end of a compound sentence. Examples of subordinating conjunctions include "although," "while," "because," "since" and "if," among others. A comma is rarely used when the dependent clause is in the second half of the sentence, as in the following example: "I chose to meet up with friends for lunch rather than eat alone." When the sentence structure is reversed, a comma must be used: "Rather than eat alone[,] I chose to meet up with friends for lunch."
Conjunctive adverbs link multiple ideas in a composition by either combining two independent clauses or relating to information conveyed in a previous sentence. "However," "also," "nonetheless" and "moreover" are examples of conjunctive adverbs. The position of the adverb and the structure of the sentence determine how it is punctuated. Conjunctive adverbs positioned between two independent clauses combine two individual ideas that must be separated by a semicolon and a comma. The following sentence offers an example: "The facility is not up to government standards[;] therefore[,] it must be closed until the criteria are met. A conjunctive adverb at the beginning of a simple sentence is followed by a single comma, but when it appears at another position in the sentence, the adverb is preceded and followed by commas. For example: " The children[,] however[,] will need to return home in time for bed."
The coordinating conjunction "and" is frequently used to separate a series of items listed in a sentence, such as "coats, hats[,] and gloves." It is correct to include or exclude the comma before the conjunction in a series depending on the preference of the writer or professional requirements. The Associated Press style of journalistic writing is one standard that considers the serial comma unnecessary. In a short series, you can avoid the use of commas entirely by including the conjunction more than once. For instance, "and" links each item in the sentence, "My hat and coat and gloves are all in the closet."