Coordinating conjunctions join two or more elements of equal grammatical rank, such as words, phrases, or independent clauses. In English, the main coordinating conjunctions are 'and,' 'but,' 'or,' 'nor,' 'for,' 'so,' and 'yet.' They create coordination, not subordination. A coordinating conjunction can join clauses to form a compound sentence. Punctuation depends on what is being joined and the length of the clauses.

Rule
A coordinating conjunction joins elements of equal grammatical rank.
When joining two independent clauses with a coordinating conjunction, use a comma before the conjunction.
When joining single words or short phrases, a comma is usually not needed.

'And' adds information by linking similar or related ideas. It can join nouns, verbs, phrases, or clauses with equal value. In a list of three or more items, English often uses a comma before 'and' in writing, called the serial comma. The meaning is additive, not contrastive or alternative.

Word/Phrase	Definition
and	'And' connects similar ideas or items to add information.
the serial comma	The serial comma is the comma before 'and' in a list of three or more items.
both ... and	'Both ... and' emphasizes that two things are included together.

'But' connects two ideas and signals contrast or exception. It can join words, phrases, or independent clauses of equal rank. When joining two clauses, a comma usually appears before 'but' in writing. The meaning focuses on difference or limitation between the joined elements.

Word/Phrase	Definition
but	'But' connects two ideas with a contrast.
not ... but	'Not ... but' highlights replacement or correction of one idea with another.
yet	'Yet' signals contrast with a sense of unexpectedness, similar to 'but.'

'Or' presents alternatives or choices between two or more options. It can join words, phrases, or clauses that are grammatically parallel. In questions, 'or' often introduces options for selection. In lists, clarity may require repeating 'or' or using the serial comma in writing.

Word/Phrase	Definition
or	'Or' presents an alternative or choice between ideas.
either ... or	'Either ... or' introduces two alternatives, with the expectation of one.
nor	'Nor' joins negative alternatives, often after a negative context.

'So' joins clauses to show result or consequence. When 'so' functions as a coordinating conjunction, it links two independent clauses and usually takes a comma before it in writing. The relationship expressed is cause and effect at the same grammatical level. This use is different from 'so' as an adverb or as a marker in subordinate clauses.

Rule
'So' as a coordinating conjunction links two clauses with a result, and a comma usually comes before 'so.'
'So that' introduces purpose and creates subordination, not coordination.

'For' as a coordinating conjunction introduces a reason, similar to 'because,' but keeps the clauses coordinated. It is more formal or literary than other conjunctions in modern English. When used to join two independent clauses, a comma typically appears before 'for.' This use is different from 'for' as a preposition.

Rule
'For' as a coordinating conjunction introduces a reason and usually takes a comma before it.
'For' as a preposition does not coordinate clauses and does not take a comma for coordination.

Coordinating conjunctions can join two independent clauses to form a compound sentence. Each clause must be able to stand alone as a complete sentence. In standard writing, a comma is placed before the conjunction when joining two independent clauses. Joining without a conjunction can create a run-on sentence or comma splice.

Rule
When two independent clauses are joined by a coordinating conjunction, use a comma before the conjunction.
Each joined clause should be complete, with its own subject and verb.

Coordinating conjunctions link items in a list, commonly with 'and' or 'or.' In English writing, a list of three or more items may use the serial comma before the final conjunction. The choice to use the serial comma can depend on style guides, but the conjunction still marks the last item. Parallel structure helps keep lists clear and grammatical.

Rule
In a list of three or more items, 'and' or 'or' links the last item.
The serial comma is optional by style but can increase clarity in a list.

Coordinating conjunctions connect equal elements to combine ideas without creating dependence. The core set is 'and,' 'but,' 'or,' 'nor,' 'for,' 'so,' and 'yet.' Correct use depends on meaning (addition, contrast, alternative, result) and on parallel grammatical structure. In writing, a comma before the conjunction is standard when joining two independent clauses.