What a Microsoft 365 tenant is, and what provider-managed means
A tenant is your own Microsoft 365 organisation account. It is where your users, mail, files, Teams chats and security settings live. Every Microsoft 365 customer has one, whether they know it or not.
The question is who owns and controls it.
Owning your own tenant means your business is the registered owner. You hold the global administrator account. You decide who your Microsoft partner is, and you can change that partner whenever you want without moving a single email.
A provider-managed tenant is one your reseller created and controls on your behalf. They hold the keys. You get a cut-down view, or sometimes no real admin access at all. Your licences, your domain and your data sit inside an account the provider owns. To Microsoft, the provider is the official account holder, and you are a line on their bill.
The difference only matters on the day you try to leave. With your own tenant, leaving is a billing change. With a provider-managed tenant, leaving can mean a migration you did not plan for, because the provider has no reason to make the exit easy.