Coordinating conjunctions join grammatically similar elements (two nouns, verbs, modifiers, or independent clauses), and indicate the elements are equal in importance and in structure. When you're trying to remember what a coordinating conjunction is, just think of FANBOYS:
When you use one of the FANBOYS to connect two complete sentences, put a comma before the coordinating conjunction.
Example: Perhaps all budgets contain some fat, but university officials argue that their unique function requires special standards of evaluation.
When either independent clause in a compound sentence contains a comma to set off introductory or non-essential elements, a reader may be confused by a comma before a coordinating conjunction. In this case, a semicolon may replace the comma.
Example: The figures at elite universities, particularly, are enough to cause shock; yet the current increases at many schools are the lowest in a decade.
If a sentence begins with a coordinating conjunction, it is not followed by a comma.
Example: Yet the typical tenured professor’s salary of $43,000 still represents 10% less buying power than the equivalent salary in 1970.
Commas are not used between two verbs, subjects, complements, or objects joined by a coordinating conjunction.
Example: That confuses most universities and profit-making enterprises.
Conjunctive adverbs (or sentence adverbs) indicate a connection between two independent clauses in one sentence, or they may link the ideas in two or more sentences. They may also show relationships between ideas within an independent clause.
When a conjunctive adverb connects two independent clauses in one sentence, it is preceded by a semicolon and followed by a comma, avoiding run-ons and comma splices.
Example: Tuition increases, say officials, are driven by the universities’ costs; consequently, tuition income typically covers less than 50% of college budgets.
If a conjunctive adverb is used in any other position in a sentence, set it off with commas.
Example: Nonetheless, some colleges are making efforts to trim budgets.
Example: Secretary Bennett, however, maintains that more federal aid would encourage universities to count on the government to meet any increases they might impose.
Compiled from the UW-Madison Writers' Handbook