The Oxford Comma, why it must be used for semantic meaning, and correct grammar use of syntax, and why it is not optional.

It, (the oxford comma) is not optional, there is a correct way to write, and an incorrect way to write.

 Notice, how I used a comma to separate each segment of syntax, (It is not optional) it is there to designate it as a complete thought, a segment of grammar, a finished statement within the sentence structure, yet I did not end it with a period. Why? I continued to use a comma to designate it as being part of the next segment of structure and therefore needed for semantic understanding, interpretation, and clarity.

It shows you, that you, must, interpret it all as a whole, and not separate.

It continues, that sentence, and designates it as part of the semantic interpretation of that structure, needed for clarity.

If it really was separate, as a structure or clause, and could be removed or separated, then it is not needed for understanding of the relevant, right or left of the segment.

Those, the relevant right, and if highlighted and rhemed, or moved to important focus, it goes to the left.

If there is a comma, then interpret anything to the relevant right, or relevant left, if topicalized, rhemed, focused upon ,highlighted for important consideration, as being connected, and anything separated with conjunctions (fanboys) the word and, and  no comma as being a part of a completely different independent sentence, and its semantic understanding. If it has and , and no comma, then it as a sentence could be removed entirely without affecting the whole semantic meaning and understanding.

It topicalizes, the segment of grammar,syntax, to the relevant left, and moves the rheme and focus to it, as being more important, as an element in the overall structure. The relevant right is used as the primary semantic meaning and understanding of any part of syntax, when it is moved to the relevant left, therefore it is rhemed, focus is put upon it as the most important thing to understand, then it is found on the left of the segment of grammar.

So it (the oxford comma)  is not optional, it is required for interpretation and semantic clarity, to designate that the prior part of syntax is relevant to the interpretation of the rest of the sentence or what follows, to leave it out, and not add it means it is a completely different sentence, and clause, and can be removed without affecting semantic interpretation or meaning.

When punctuation is used to (end-stop) any phrase or clause it means that unless it is a period, a full stop, then the preceding segment is needed, and can not be separated from the understanding and interpretation. It is necessary and required.

If you were taught correctly, you would understand that concept of how, and in what way the punctuation is used correctly for semantic understanding, and communication.

 Note I kept using commas as each part added to the rest and helped you understand it is needed to be connected, to be understood as a whole.

I did not write: When punctuation is used to (end-stop) any phrase or clause it means that unless it is a period, a full stop, then the preceding segment, is, needed { and can not be separated from the understanding and interpretation. It is necessary and required.}

Why didn't I NOT leave out the comma? It is because you NEEDED the second sentence for clarification, without it, then it does not make full clear semantic sense.

Also, as it is equal to it I could have used a semi colon (;) but didn't, why? That is because it was not a separate sentence that could be completely removed without the meaning altered or changed. It required it as part of the sentence for semantic meaning. To interpret it properly.

If it was a completely separate sentence independent clause I would just use a semi colon to separate, and designate it of equal importance in value and consideration.

https://www.youtube.com/watch?v=ptM7FzyjtRk