Use of Commas
1) Separate dependant clauses if they are placed at the beginning of a
sentence.
2) Separate two independent clauses that use a coordinating conjunction:
and, but, or, nor, for, yet and so. If the independent clauses are short you
can omit the comma. If the clauses are long and complex you can
separate with a semi-colon.
3) To avoid run-ons and comma faults: two independent clauses not
separated by conjunctions or commas.
4) Use it to separate three or more items in a series. Elements in the series
can be short independent clauses.
5) Use it between adjectives of different categories that modify the same
noun. If the adverbs or adjectives modify other words in addition to the
noun, then do not use commas.
6) Use a comma for clarity, for example between identical words or to avoid
confusion.
7) Use commas to set off some elements.
8) Use commas for parenthetical phrases, disruptive or out of order ones.
9) Non defining clauses.
10) For appositive phrases.
11) Direct address
12) Introductory phrases
13) After abbreviations
14) Conjunctive adverbs