Scavenging, foraging, looting.

[John]

Scavenging, foraging, looting.
We are talking post SHTF here, probably from 6 months to a year, may be more, after the event. Probably not many people around.
So what is scavenging, what is foraging and what is looting. When do these, if at all, change their meaning? Do or are any of them acceptable in the above situation or do they become acceptable?

To help below are what the dictionary says.
Forage
1. Food for domestic animals; fodder.
2. The act of looking or searching for food or provisions.
3. To wander in search of food or provisions.
4. To conduct a search; rummage.
Looting
1. Valuables pillaged in time of war; spoils.
2. Stolen goods.
Scavenge
1. To search through for salvageable material
2. To collect and remove refuse from
3. To collect (salvageable material) by searching.
4. To search through refuse for useful material.

So you decide it is time to venture out, may be your stocks are getting a little low, how do you decide what is what.
When, if ever is it OK to take what is not yours, how do you decide that no one is around or alive now who owns an item and that it OK for you to take that item.
One last question, your are desperate, may be on the verge of starvation, would it be right, in the situation above, to steal from another.