FANBOYS (coordinating conjunctions)

FANBOYS stands for for, and, nor, but, or, yet, so — the seven coordinating conjunctions. A coordinating conjunction connects elements of equal grammatical weight: two nouns, two verbs, two phrases, or two independent clauses (word groups that could each stand alone as a sentence).

The rule tested most often involves joining independent clauses. Two complete sentences can be combined with a comma plus a FANBOYS word: "I studied all week, so the exam felt easy." Drop the conjunction and keep only the comma, and you create a comma splice — a classic sentence error. Drop both and you have a run-on. When a FANBOYS word joins just two elements smaller than independent clauses, no comma is needed: "I studied math and science." The exception is a series of three or more items, where a comma still precedes the conjunction: "I studied math, science, and history."

Coordinating conjunctions also carry meaning. And adds, but and yet contrast, or offers alternatives, nor continues a negative, for gives a reason, and so shows a result. Choosing the conjunction whose logic fits the sentence is itself a tested skill, especially in transition questions.

The ACT English section, the SAT Writing portion, and the Praxis Core Writing exam all test FANBOYS heavily — most often as comma questions. When you see a comma before one of these seven words, check whether a full independent clause follows: if yes, the comma is correct; if no, the comma usually needs to go — unless it is separating items in a series.