Well

Well, manmade hole in the ground used to tap water, gas, or minerals from the earth. Most modern wells are drilled and fitted with a lining, usually of steel, to forestall collapse. Though wells are sunk for natural gas and petroleum oil, the most common type yields water. Such wells may be horizontal or vertical, but all have their innermost end below the water table. If it should be below the permanent water table (the lowest annual level of the water table), the well will yield water throughout the year. Most wells require pumping, but some operate under natural pressure.