This is olive tree, gold of the Mediterranean, the inexhaustible source of the famous oil.
It’s said that the word “oil” is appeared from the word “olive”.
Earlier buying canned olives, I thought that their color depends on the type of tree only. But looking at these trees, where olives of different colors coexist, it seems that the degree of ripeness of the fruits does matter also.
If you would like to see the process of olives' gathering, you can see the videos published by George Tube and OxboInternational using the links