Crude oil is composed of many different kinds of hydrocarbons, and can be broken down or refined to produce a wide spectrum of things.
The main product of petroleum is gasoline. This is used to fuel engines, and is a volatile mixture of lighter petrochemicals.
The second most common product of crude oil is diesel. Diesel is similar to gasoline, but is heavier and less volatile than it's fuel cousin. Diesel is also used to run engines, but can only be used in special engines designed with the lower volatility in mind.
A significant portion of crude oil is used to make jet fuel, which is similar to diesel in composition but contains a different concentration of sulfur and has different lubrication properties. Neither diesel nor jet fuel will catch fire in the presence of an open flame, but both still contain lots of energy.
Some oil is used to make heating oils for lamps and burners, and is similar to diesel.
Crude oil can be used to make lubrication oils, which do not burn easily and can maintain lubrication at extremely high temperatures. These oils are used in engines, mechanized parts, windmills, and any other type of joint or hinge.
Gas products, such as propane and butane, are extremely volatile and burn easily. These are used in lighters, heaters, grills, and stoves.
Solvents are made with crude oil, and work very well on organic material like rubber and plastic.
Rubbers and plastics are made with crude oil or components of crude oil.
A vast portion of crude oil is used to generate electricity, particularly the liquid fuels and gasses like gasoline, diesel, and propane.