Oil forms from dead plant and animal life drifting to the bottom of the ocean and it there is covered with sand and sediment material. Over thousands of years due to high temperature and pressure these fossils form oil. Oil is mainly used in developed western countries such as Australia, Canada, USA and some European Countries, who mainly use oil for energy and fuel for automobiles. Oil is a precious commodity and it is very expensive. It is believed that the worlds oil reserves will run out within the next 40-50 years.
Oil is so valuable that is was the main reason why the Gulf War began.
As it is so expensive underdeveloped countries can sometimes not afford it even though they desperately need it for transport, which stops their countries growth. So as you can image if one of these ships started to leak it would have a serious detrimental effect on the environment. Oil spills can cover a massive area. It took a long time for this region to recover. To prevent oil spills, I feel oil companies must be so accurate that every part of the tanker is leak proof.