Overhead cables are made of almunium not of copper explain?

Much of the newer overhead cables is made of aluminum with steel reinforcing it for strenght purposes. Aluminimum is much cheap, and much lighter, thus it is cheaper to use vs. copper for high voltage transmission, and copper has a lower resistance which means more electricity can get through the wire/ cable, which means more electricity can get around the world quicker. most people should use copper becasue it has a lower resistance where aluminuim has a bit of a high resistance not to much but a bit so that is why you use copper not alominuim.