What it is:
An oil field is land that contains oil.
How it works/Example:
Specifically, an oil field contains oil that is trapped by a layer of rock. Oil fields are notoriously difficult to locate and tap.
Why it matters:
There are thousands of oil fields on Earth, some of which are at the bottom of the sea. These oil fields are the source of much of the world's oil, and many companies spend millions of dollars locating and drilling in oil fields. The fuel obtained from these fields can become gasoline, plastic, jet fuel and a variety of other products.