Is a comma used after the words yes no why and well when they are first in sentence?

That's a great question! It depends on the context and the structure of the sentence. Here's a breakdown:

Yes/No:

* Generally, no comma is needed. "Yes, I can help you." is incorrect. "Yes I can help you" is correct.

* Exception: When followed by an independent clause. "Yes, I will be there tomorrow." Here, "Yes" is a short interjection, and the comma separates it from the main clause.

Why/Well:

* Generally, no comma is needed. "Why did you do that?" "Well, I had to."

* Exception: When followed by an independent clause. "Why, that's the most beautiful sunset I've ever seen!" "Well, I'm glad you think so."

In Summary

Think of "Yes," "No," "Why," and "Well" as words that introduce a sentence or thought. If they are followed by a complete sentence (an independent clause), use a comma. Otherwise, no comma is needed.

Let me know if you have any other questions!