Here's why:
* "Yet" is an adverb that typically introduces a contrasting or opposing idea. It's not a conjunction like "but" or "and," which would require a comma after them.
* Using a comma creates a pause that doesn't make grammatical sense. It would sound awkward and disjointed.
Example:
* Incorrect: Yet, the cat sat on the mat.
* Correct: Yet the cat sat on the mat.
However, there might be some exceptions:
* If "yet" is part of a phrase or clause that functions as a parenthetical element:
* "The cat, yet still a kitten, was already quite mischievous."
In this case, the comma is used to set off the parenthetical phrase "yet still a kitten."
* If "yet" is followed by a strong pause or a change in thought:
* "Yet, I still feel a pang of sadness when I think of him."
This use is less common and depends on the specific context and the desired tone.
In most cases, it's best to avoid using a comma with "yet" at the beginning of a sentence. It's more likely to create a grammatical error than to improve clarity.