Oh. I didn’t know there was such an animal. (I’m old.)
It’s new with Windows 10.
It is linked to a Windows App called “People” that contains all your contacts and shares them with other apps, like Office, so that if you type the first few letters of that contact in a letter or email it automatically inserts that contacts. I turned it off and deleted it, thinking that was the problem but the old contacts from the previous user are still there...................