What is a river's source?

A river's source refers to the location where the river begins its journey, which is often in high elevations such as mountains or hills. This is the point where precipitation or melting snow collects and starts flowing downhill due to gravity, forming the river. The source can be a spring, a glacier, or even a rainwater overflow.

The source is critical in the river's lifecycle as it usually determines the river's characteristics and flow patterns as it travels towards its mouth, where it eventually meets the sea or a larger body of water. In contrast, meeting the sea indicates the river's mouth, while splitting into multiple channels refers to the river delta or distributaries, and flowing through flat plains describes the river's journey in its middle or lower course. Each of these points plays an important role in the river's overall system but does not define where it originates.