The seven coordinating conjunctions — for, and, nor, but, or, yet, so (FANBOYS) — join grammatically equal elements: words to words, phrases to phrases, or independent clauses to independent clauses. When joining two independent clauses, a comma precedes the conjunction (She studied hard, but she still struggled with the test). Each conjunction carries a distinct logical meaning: "and" adds, "but" contrasts, "or" offers alternatives, "so" shows result, "for" explains cause, "yet" introduces surprise, and "nor" negates an additional option.
Memorize the FANBOYS acronym, then practice identifying which type of elements each conjunction is joining in real sentences. Pay special attention to whether a comma is needed — it depends on whether full clauses or just words/phrases are being connected.
You already know from your study of prepositions and conjunctions that conjunctions connect elements. Coordinating conjunctions take that idea a step further: they join elements that are grammatically equal — the same rank on each side. Think of them as a balance beam. Whatever is on the left side of the conjunction must match the grammatical type of whatever is on the right: a noun joined to a noun, a verb phrase to a verb phrase, or a full independent clause to another independent clause. The FANBOYS acronym (for, and, nor, but, or, yet, so) is a reliable memory device because there are exactly seven, and you need to know all of them.
Each conjunction carries a specific logical relationship. And adds without tension. But introduces contrast or restriction. Or presents alternatives. So signals that the second clause is a result or consequence of the first. For introduces a reason (similar to "because," but more formal). Yet contrasts like "but" while also conveying surprise — something happened despite an expectation to the contrary. Nor negates an additional option, typically following a negative statement ("She didn't call, nor did she text"). Using the wrong conjunction can subtly or dramatically change your meaning, so precision matters.
The comma rule is the most immediately practical skill. When a coordinating conjunction joins two full independent clauses — each with its own subject and verb — place a comma before the conjunction ("She studied all week, but the exam still surprised her"). When the conjunction joins only words or phrases — not full clauses — no comma is needed ("bread and butter," "tired but happy," "slowly or quickly"). A reliable test: can each part stand alone as a complete sentence? If yes to both, use the comma. If no — if one side is just a word or phrase — skip it.
A final nuance worth building into your understanding: coordinating conjunctions are one of three main ways to join clauses (alongside subordinating conjunctions and semicolons), and they signal a specific relationship — one of equality. Neither clause is subordinate to the other. This is fundamentally different from "although," "because," or "while," which establish a main clause and a dependent one. When you choose a coordinating conjunction, you are telling the reader that both ideas carry roughly equal weight.