What is the term for the beginning point of a river?

The term for the beginning point of a river is known as the source. The source is where the river originates, typically found in highland areas such as mountains or hills, and it can be a spring, a melting glacier, or rainfall. It is the starting point where water begins its journey, flowing downhill through various landscapes and eventually merging into larger bodies of water.

Each of the other terms refers to different aspects of a river's journey. The mouth refers to the end point where a river meets an ocean, sea, or lake, often resulting in a delta or estuary. An estuary is a coastal area where freshwater from rivers meets and mixes with saltwater from the ocean. A delta is a landform that develops at the mouth of a river, where sediment carried by the river is deposited as the river slows down upon entering a larger body of water. Understanding these definitions helps clarify the distinct phases in the life cycle of a river.