Commas (,) are used after yes, no, and well at the beginning of a sentence.
Yes, the pasta was delicious!
No, I have not seen your cat.
Well, it was raining, so we stayed inside.
We use a comma after each item except the last one in a series of three or more items.
Zebras, elephants, and giraffes live in the safari.
Dogs, birds, cats, and rabbits are pets we have at home.
Janet, Marcus, and Ariel are playing blocks together.