Not necessarily. A comma indicates a pause in speech, or separates ideas for clarity. Where there is no pause and no possible confusion there should be no comma.
There is no comma before Jr.
It is usually appropriate to place a comma before "but." One should not use a comma after "but."
before
No, a comma is not necessary.
no
no
no
You would use a comma before it. Xerox, Inc.
I do not use a comma before and after that word, therefore you will not see it in any sentence I have written.
You add the comma before the connector.
if the main or most important part is before the main parts you use a comma, but if it is after then no comma
Sometimes a comma is needed before a name in a sentence. An example of when to use a comma before a name is, my boyfriend, Carl, went to Yale.