How can I tell if a cat is feral?

Hi, I live in a gated neighborhood with about 80 houses that are all right next to each other with small backyards.
I've noticed a few of the same cats wandering around and I'm not sure how to tell if they are feral or not.
I always see the same 4 cats one orange and white, one black, and the two others I've only seen in the dark so I'm not really sure I think one is white with patches of brown.
They don't have collars on and they don't let me get near them. We put some food on our ledge of our concrete fence and food was always all gone.
I've also noticed the person at the end of the neighborhood keeps food and water out on the side of their house, do you think it could be their cats? Or could they be leaving the food out for strays?
Is there a certain way to tell if a cat is feral or not? If they are I want to help them feed them and maybe make a warm spot for them to sleep in the winter. Is it okay to just leave a cat outside and feed it? I feel bad for the cats.
Any advice for me?
Thanks - Megan

It sounds like they are strays or feral. The ones that come out only at night are most likely feral. Usually, feral cats avoid human contact. Why don't you talk to the neighbor who leaves food out? If he/she hasn't had the cats fixed, perhaps between the two of you, you will be able to have them all fixed and provide them with shelter.

Their lives will be vastly improved with this. You may find that some of them at least will become tamer and perhaps become house cats. Even if they don't become pets, you will be doing such a kind thing for them.

Thank you for helping them!

Hopefully you can calmy have a conversation with your neighbor -chances are they share your worry about the kitties. And maybe you can trade off feeding responsibities -lightening everyone's load! The two big keys as winter comes knocking - getting them fixed (so there aren't 4 times as many next spring!!!!!!!) & finding the some form of shelter. Have you had any luck in contacting the other feeder? These guys probably can really use some kind-hearted help!

You can look up "low cost spay neuter" plus your county/city to find assistance with spay and neuter surgery and probably they can also tell you where to get help with trapping them, if they have to be trapped. Or ask the local shelter(s).

There is  plenty of information online on how to build winter shelters for feral cats.

Yes, as the others have said, neutering/spaying is essential, and then you can work on keeping them fed and warm.. We have articles (some listed below) and also very knowledgeable members who can offer advice and support....  Just ask. 

[article="30118"]10 Facts You Should Know About Feral Cats​[/article]

 [article="32879"]9 Practical Ways For You To Help Feral Cats​[/article]  

 [article="32458"]How To Help Feral Cats Stay Safe Warm During Winter​[/article]