But consider the Oxford comma - also known as the Harvard comma. It's put before and to resolve ambiguity.

My favourite types of sandwiches are Marmite, jam, cheese and ham and tomato.

It's not clear whether that list includes a cheese and ham sandwich and a tomato sandwich; or a cheese sandwich and a ham and tomato sandwich.

My favourite types of sandwiches are Marmite, jam, cheese, and ham and tomato.

Now that makes it clear.

Sometimes it's put before and at the end of a list of three things, if it's possible that the first item could be made up of the second two. Wikipedia reports the apocryphal book dedication:
To my parents, Ann Rynd and God.

You make it clear by putting in a final comma:
To my parents, Ann Rynd, and God.


Thank you