Will An Old Apple ID Still Be Connected To an Iphone That Has Been Factory Reset?

Ok so heres the thing, I was sold an iphone by someone. I did a factory reset on the phone through the iphone itself. I asked a question before on here about whether the phone is now completely mine officially that it has been restored. But I still have a sense of concern because i will never see this guy again (not like hes a bad guy but i just won't see him) and i wanted to know if his apple id will still be connected to this phone even after a factory reset? When i did the reset i didn't have to put in a password or anything it just reset itself. Does that mean he didn't have an apple id in the first place if i didn't have to put in a passcode to reset? Or will i find out otherwise when i connect to itunes? I don't have a computer of my own yet to connect to itunes right now. What is an apple ID and do all iphones have it? I just don't wanna be stuck with a phone i can't use after i've already paid for it.

No, it won't once reset is done, it means no ID is connected and once your add your own ID to this device that becomes the ID attached to it moreover go to iCLOUD and activate the account and preferably the find my iphone service