My fault for not giving a complete answer.
You still need permission to hunt (or fish) on land you don't own, but if it is not posted, oral permission is fine. Probably 90 -99% of the deer hunting in Georgia occurs on land where the hunter only has oral permission.
Funny story here about that. We caught a couple of fellows turkey hunting on our deer lease. They claimed they had permission, and I asked them who gave that permission. One of them popped off right away, "gh1950". so I ask him "so what does he look like?" Course he didn't know, and we escorted them off the property. But it was fun moment.
The corollary to this, is that you see questions on interweb forums all the time about " there's this tract of land that is owned by ????. is it o.k. for me to hunt it. The short answer to all those questions, is that if you don't have express permission from the owner, it's not o.k.