EXCEPT

Although the word “except” apparently originated as a verb, it is most commonly used as a conjunction or a preposition nowadays. Its listed meanings as a conjunction include “only,“ “under any other condition than,“ and “with the exception of.” As a preposition, it may indicate “not including,” “but not,” and “other than.” It is when it functions as a conjunction, often taking the place of the coordinating conjunction “but,” that it requires a comma, which alerts the reader to the beginning of a new idea that can almost, if not entirely, stand on its own. Sometimes “except” is used to introduce a parenthetical statement (i.e., information that could be put in parentheses since nonessential). Such parenthetical  information is set apart by two commas if in the middle of a sentence.


Apart from use as verb “omit,”
“Except” is typed as one of two.
Conjunction may it be when writ
Or preposition if more true.

Its meaning when in latter role 
Is “not including,” “other than,”
“But not,” or other such by soul;
Perhaps more stout in kindred stance.

Conjunctions join distinct ideas,
Not simple noun to single word.
“Except” when serving thus most days
Will boast a comma, strength assert.

Between two independent parts
Or adding on dependent clause,
Like parentheticals apart,
It sports the comma, marks its cause.

“The trees are mainly thick and green,
Except they thin along the cliff.”
“The rushing wind will howl and keen, 
Except when not so very stiff.” 

The case of parentheticals
Is easily seen and commonly known:
“Some tools, except mechanical,
Were hung on pegs as if there flown.”

If prepositional is the use,
No comma stands to tout the event.
Except at start of sentence news, 
It quiet comes, no notice sent.

“The meeting had already begun 
When cautiously he took a peek.
He knew he had to get it done;
The door was safe except for squeak.”

The key for commas with “except”
Boils down to knowing part of speech.
Put parentheticals aside,
And spot conjunctive usage each.
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