Update 2020-11-06: Rename this article to be more obvious and updated some of the code, along with learnings from the past few years.
Tableau can do Multi-Tenancy. But your database might also, in a variety of ways, also do what you think of as “multi-tenancy”.
In years having this discussion, I have learned one thing: Multi-Tenancy is used differently by everyone to describe these structural organizations. So we have to be very clear to make sure we all are talking about the same things. That makes this article a bit long-winded (surprising for me I know!), but hopefully the precision justifies the extra words.
If you are using Tableau to present data to multiple different organizations (customers, clients, suppliers, hospital groups etc.), the structure of how you store that data greatly affects the way you should organize content on Tableau Server.