Petroleum geology is the study of origin, occurrence, movement, accumulation, and exploration of hydrocarbon fuels.

A petroleum geologist is an earth scientist who works in the field of petroleum geology, which involves all aspects of oil discovery and production.

Petroleum engineering is a field of engineering concerned with the activities related to the production of Hydrocarbons, which can be either crude oil or natural gas.

Petroleum coke, abbreviated coke or petcoke, is a final carbon-rich solid material that derives from oil refining, and is one type of the group of fuels referred to as cokes.

Petroleum also known as crude oil and oil, is a naturally occurring, yellowish-black liquid found in geological formations beneath the Earth's surface.

Petrol engine (British English) or gasoline engine (American English) is an internal combustion engine with spark-ignition, designed to run on petrol (gasoline) and similar volatile fuels.

Petrochemicals are the chemical products obtained from petroleum by refining.

Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection.

Perpetual motion is the motion of bodies that continues forever in an unperturbed system.

A perovskite solar cell is a type of solar cell which includes a perovskite-structured compound, most commonly a hybrid organic-inorganic lead or tin halide-based material, as the light-harvesting active layer.

The permissible exposure limit (PEL or OSHA PEL) is a legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as high level noise. A PEL is usually given as a time-weighted average (TWA).

Permeability is the measure of magnetization that a material obtains in response to an applied magnetic field.

Permanent magnet generator (PMG) is a synchronous electrical generator design based on the use of permanent magnets on the rotor.

A permanent magnet is an object made from a material that is magnetized and creates its own persistent magnetic field.

Permafrost is ground that continuously remains below 0°C (32°F) for two or more years, located on land or under the ocean.

The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties.

The period is the duration of time of one cycle in a repeating event, so the period is the reciprocal of the frequency.

Performance-based regulation is an approach to utility regulation designed to strengthen utility performance incentives.

A pyrometer is a type of remote-sensing thermometer used to measure the temperature of distant objects.

Pyrolysis oil, sometimes also known as bio-crude or bio-oil, is a synthetic fuel under investigation as substitute for petroleum.