Paris, France, is sometimes called "The City of Lights. Use a comma to separate introductory elements in a sentence from the main part of that sentence.
When two complete "sentences" are merged into one using a conjunction, the conjunction should be preceded by a comma.
Generally speaking more on this belowAmericans will use a comma, but Brits won't. The picture in your mind adapts to the comma and conjunction.
In newspaper writing, incidentally, you will seldom find a serial comma, but that is not necessarily a sign that it should be omitted in academic prose. When that is the case, you can use a conjunction to pull them together and paint them happening at the same time in your brain.
If there is ever any doubt, use the comma, as it is always correct.
Be the best writer in the office. Now the comma part of all this… And the Comma