how do you know stray is really a stray?

There is a stray cat that has been hanging around my house for around 2 months.I feed and water him.Every other day he will disappear for a day and then come back.He is not fat,but not too skinny.He has no tags or collars.One of my other neighbors went knocking door to door asking ppl if this was their cat,and the immediate neighbors said no.But I live in a community where there is a high turnover rate of ppl moving in and out.So I figure its either a new person or a person that just left and abandoned their cat.But I figure that even if someone does own this cat,they dont take care of it because it is very dirty and ravenously hungry every time I feed him.I was thinking about taking him to the vet for vaccinations but how can I know if this cat belongs to someone?Maybe there really isnt a way to know.
P.S. He is not a feral,because he is VERY friendly.He loves to be petted and held.

It's really tough - you can never be sure. But you are doing the right things - asking around to see if anybody owns the cat. You could try looking at any lost and found registers. Alternatively, if you capture the cat, and this seems like a really good idea from what you say, you could take it to a vet that can scan for a microchip. If the cat was owned before but somehow got separated from its owners, it may be friendly anyway; so that in itself is no guarantee that the cat has a home.

We had the same issue with Adelaide. She had no collar and was quite frightened, but still approachable to some extent. She wasn't skinny but was ravenously hungry. We did the same as you and took her to the vet who scanned for a microchip, but couldn't find one.
Thank you for taking care of this poor hungry kitty

I would take him to the vet...but I would have the vet check to see if he has been neutered....and if he isn't..I would have the neutering performed at that time in addition to having him brought up to date on shots.

Katie