MDM · Apple
Managed Apple ID
An Apple account your organization creates and controls through Apple Business on your domain — you can reset, reassign, or revoke it.
A managed Apple ID is an Apple account that your organization creates and controls through Apple Business, on your own domain — as opposed to a personal Apple ID an employee sets up themselves. Because the organization owns it, you can reset it, reassign it, and revoke it when someone leaves.
The contrast is the whole point. When work apps, devices, or data are tied to a personal Apple ID, you have no control: when that person changes roles or leaves, updates break, password prompts appear that nobody can answer, and licenses are stranded. Managed Apple IDs keep all of that under organizational control.
They're also a prerequisite for more advanced capabilities like device trust on personal iPhones, where a managed Apple ID is what links the device to your organization securely. Managing your Apple IDs from the start avoids a painful cleanup later, when people will otherwise have accumulated personal Apple IDs on your domain through the wrong channels.