A spring is a location where underground water finds an opening through surface of the land and emerges to form a trickle, a small pool, a creek or stream or even a gushing forth of a river. Too, spring water can also emerge from heated rock underground, giving rise to hot springs, which often will be contained into a pool of water for soaking the body.

This is a spring that typically occurs at the lowest point in a given area. An artisan spring is created when the pressure for the groundwater becomes greater than the pressure from the atmosphere. In this case the water is pushed straight up out of the ground.

This spring occurs along the side of a hill or mountain and is created when the groundwater is under layered by an impermeable layer of rock or soil. This layer is known an aquiclude or aquifuge. The underground water flows along the impermeable layer until it finds a point to emerge from the ground.

This is a spring which occurs along a depression, such as the bottom of alluvial valleys, basins, or valleys made of highly permeable materials.

This spring occurs when groundwater running along an impermeable layer of rock meets a fracture or joint in the rock. Then, the underground water flows along the crack to a point where it emerges from ground.

This spring is an outflow of groundwater that is part of a karst hydrological system. This is a network of cracks, fissures and openings where water flows through to a point where the water emerges from below the surface.

This is a freshwater submarine groundwater discharge, which is a hydrological process normally occurring in coastal area.

The volume of water which flows from any springs depends on several factors. Some of these factors include: the size of the caverns within the rocks, the water pressure in the aquifer, the size of the spring basin, and the amount of rainfall.

Activities of humans can also affect the volume of water that discharges from a spring, and from their activities, can cause water levels in the aquifer system to drop and ultimately decrease the flow from the spring. Most people probably think of a spring as being like a pool of water, which is usually correct. However, springs are not necessarily always naturally created but can be caused when geologic, hydrologic, or human forces cut into the underground layers of soil and rock where water is in movement.

Springs are often classified by the volume of water that is discharged from the spring, which volume is called from a first magnitude to eighth magnitude.

1st magnitude has greater than 100 cf/s. (>750 g/s)

2nd magnitude has from 10 to 100 cubic feet per second. (75 - 750 g/s)

3rd magnitude has from 1 to 10 cubic feet per second. (7.5 - 75 g/s)

4th magnitude has from 100 g/m to 1 cubic feet per second. (750 g/m - 7.5 g/s

5th magnitude has from 10 to 100 gallons per minute.

6th magnitude has from 1 to 10 gallons per minute.

7th magnitude has from 1 pint to 1 gallons per minute.

8th magnitude has less than 1 pint per minute.

Minerals become dissolved in the water as it moves through the underground rocks. This mineral content is referred to as total dissolved solids (TDS). This may give the water flavor and even carbon dioxide bubbles, depending on the nature of the geology through which it passes. This is why spring water is often bottled and sold as mineral water, although the term is often the subject of deceptive advertising.

Mineral water contains no less than 250 parts per million (ppm) of tds. Springs that contain significant amounts of minerals are sometimes called mineral springs. Some springs without such mineral content, are sometimes distinguished as sweet springs. Springs that contain large amounts of dissolved sodium salts, mostly sodium carbonate, are called soda springs.

Mineral springs are purported to have healing properties and soaking in them is said to result in the absorption of the minerals from the water. Many resorts have developed around mineral springs and are known as spa towns or often hot springs towns.