An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturated lipids that are liquid at room temperature.

The general definition of oil includes classes of chemical compounds that may be otherwise unrelated in structure, properties, and uses. Oils may be animal, vegetable, or petrochemical in origin, and may be volatile or non-volatile. They are used for food (e.g., olive oil), fuel (e.g., heating oil), medical purposes (e.g., mineral oil), lubrication (e.g. motor oil), and the manufacture of many types of paints, plastics, and other materials. Specially prepared oils are used in some religious ceremonies and rituals as purifying agents.
Please describe  what is oil and give me a list of it’s applications.
An oil is a chemical substance that is composed primarily of hydrocarbons and may be animal, vegetable or petrochemical in origin.
Oil is used in a wide range of applications and is essential to everyday human life. These are:
Cooking - edible vegetable and animal oils are used for various purposes in cooking and food preparation
Cosmetics - most facial cleansers, lotions and hair care products contain molecules that come from mineral and vegetable oils
Fuel - crude oil is refined and converted to diesel, gasoline or jet fuel to power cars, trucks and planes
Heating - petrochemical oil is used for heating
Painting - oil is used as a supporting medium for paints
Lubrication - oils are used in various engineering purposes as they do not easily adhere to other substance which makes them useful as lubricants
Religion - oil has been used throughout history as a religious medium. It is often considered a spiritually purifying agent and is used to anointing purposes
Health - oils holds lots of fats and medical properties, for example fish oil holds the omega-3 fatty acid which helps with inflammation and reduces fat in the bloodstream