In the spring, water comes to the surface from the ground. This water is called groundwater. Several springs usually unite to form a stream and later a river that flows into the sea.
Most of the time it is rainwater that has seeped into the ground. It seeks its way through the earth until it emerges from a layer of rock or clay. The water cannot go through it and flows along this layer. At some point, it usually finds its way to the surface.
As water flows through the ground, it is cleaned like a filter. Springs that come from the depths usually have very clean water that can be used directly as drinking water. However, if the rainwater seeps away on a pasture or on a field with a lot of fertilizer and then immediately reappears on the surface, the water can be harmful to people.
Some springs give very warm water, these are thermal springs. The water is warm because it comes from deep within the earth where it is hot. Or it was heated by a volcano. Other sources have substances such as minerals in them. If such substances are good for the health, one speaks of a healing spring.
What else can the word “source” mean?
The word source is not only used for water that comes from the earth. “Source” often means simply the origin of a message. When something is in the newspaper, you sometimes wonder where it came from. So one wonders how the writer knows this. Maybe he saw it himself, that would be a safe source. But maybe he just heard it or read it himself somewhere, that would be an uncertain source.
There are different types of such sources. A person can be a source if he tells what he has seen or experienced himself. An old letter can be a source for historical research, but so can an old tombstone or an inscription on a house. Old paintings are sometimes good sources too. But then you have to ask yourself whether the writer or the painter might not have exaggerated.