It has been my experience that there are actually several different regional schools of comma usage. In my Fiction Writing and Style Guide, which is available as a free e-book from Bookapy and many other sites, I state the following about commas:
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Commas
There are many existing style guides, blogs, and advice articles on the use of commas, so I've no intention of going into the details of all the ways you can use a comma in a sentence. The best articles I've found are some of the Ted Ed YouTube posts, the links are below. The first is on the general use of the comma and the second is on the serial comma.
www.youtube.com/watch?v=GHnl1O3NGJk
www.youtube.com/watch?v=ptM7FzyjtRk
There are many reason why you need to use a comma, with the most common ones being: Explanatory Phrases, Introductory Phrases, and to show items in a List. However, I'll mention the serial comma first.
Serial Comma
The use of the serial comma, often called the Oxford Comma, can lead to confusion. Also, not using the serial comma can cause confusion. The experts and public are in total disagreement on using it. The choice to use it or not is allowed by style guides and leave up to the writer. What they do say is to be consistent in it's use. I tend to always use it in lists.
Explanatory Phrase
You use commas before and after an explanatory phrase, sometimes called an expansion phrase, to mark the start and end of the additional information you're providing about what was mentioned just before the starting comma. This information is an insert of more information and the commas mark the boundaries of the insertion, unless it's the last part of the sentence, then the full stop ends the insertion. Examples:
The owner, Maggie Meadows, greets us when we pull up in front of the main house.
There's a wait of several seconds, that's a very long time for a major computer.
Introductory Phrase
Is a phrase used to introduce the sentence or paragraph, but it's not directly linked to the very next phrase in the sentence, so a comma is used to separate them. Example:
"From what Joe told me, if a potential Caretaker is rejected by three new Heroes she's dropped from consideration."
Please do not regard locational phrases as introductory phrases. Too often a sentence will start with a phrase to locate the people or action in a time or place, and some writers will see this as an introductory phrase instead of the start of the main sentence phrase. It doesn't help that some of the style guides say to treat it as an introductory phrase. The problem is it often fragments the sentence. With an introductory phrase it can often be placed on the end or removed and the sentence will still make total sense in the story context, but doing that with a locational phrase will leave you a little confused.
Lists
Items can be listed one after the other on separate lines or they can be listed within the sentence on the same line where they're separated by a comma. When using commas in a list there's disagreement about the use of the serial comma which can often clarify things or cause confusion, depending on how it's used. Most people think of lists as being single items, which is the most common usage of lists. However, you can also use commas to list actions, etc. Examples are:
I decide to be brutally honest, "No, it's not. I've killed several people with a sword, a few with a knife, some by hand, and even shot a couple who needed killing. In all cases it was a matter of defending myself, or someone else, against a bad guy on everyone's 'better dead' list."
She turns, looks at me, smiles, and bows.
end quote
I hope this helps you.
BTW: One thing I've noticed is a lot of US authors use an excess of commas, especially with regards to scene and time setting phrases.