4 Basic Comma Rules: When in
doubt, leave it out.
#1 use a , to set off an introductory element from the main sentence:
In oral languages, sentence construction is also looser and less carefully planned than in written varieties of language.
This rule also applies to complex sentences (beginning with because, if, when, while, although, etc.):
If Americans in 1901 had developed email, they would likely have composed the same kind of elegant missives that they had been writing as letters...
#2 use a , to separate items in a list:
Herman is best-known for his megahits Hello, Dolly!, Mame, and La Cage aux Folles.
This rule also applies to multiple adjectives describing noun(s):
At such a cultural moment, formality [noun] becomes repressed, boring, unreflective, and even suspect [adjectives]…
#3 use a , to separate an interruption (non-essential element) from the rest of the sentence:
Anna Karenina, of all things, neatly captures what Bernstein meant.
#4 use a , to separate clauses in a compound sentence (joined with and, but, so, for, yet):
The networks restored The Voice of Firestone in 1962 after an
indignant protest, but buried it for good after one season.