Une huile est un corps gras qui est à l'état liquide à température ambiante et qui ne se mélange pas à l'eau.
Les huiles sont des liquides gras, visqueux, d'origine animale, végétale, minérale ou synthétique. Elles se différencient des graisses qui sont pâteuses dans les conditions normales d'utilisation. Le beurre n'est pas considéré comme une huile bien qu'il soit liquide dans certains pays chauds. Dans les pays tempérés, certaines huiles, normalement liquides, peuvent se figer par temps froid.
A petroleum seep is a place where natural liquid or gaseous hydrocarbons escape to the earth's atmosphere and surface, normally under low pressure or flow. Seeps generally occur above either terrestrial or offshore petroleum accumulation structures. The hydrocarbons may escape along geological layers, or across them through fractures and fissures in the rock, or directly from an outcrop of oil-bearing rock.
Petroleum seeps are quite common in such areas of the world and have been known and exploited by mankind since paleolithic times. Natural products associated with these seeps include bitumen, pitch, asphalt and tar. The occurrence of petroleum was often included in location names that developed; these locations are also associated with early exploitation as well as scientific and technological developments, which have grown into the petroleum industry.