The letter sequence FANBOYS is a mnemonic for the coordinating conjunctions, which are used to join two independent clauses: for, and, nor, but, or, yet, and so.

It is customary to place a comma after the first clause. Some prescriptive grammarians say that one should not start a sentence with a coordinating conjunction, but others do not.

See Explanation of the use of coordinating conjunctions from the NMSU Writing Center.

Mnemonics