This is where a river starts, high up in the mountains. The source, or place where the river starts from, could be a springs or a lake, or even a melting glacier. A river can have more than one source.
The source is the farthest point of the river stream from its estuary or its confluence with another river or stream. Rivers are usually fed by many tributaries. The farthest stream is called the head-stream or head water. There is sometimes disagreement on which source is the head water, hence on which is the true source. Headwaters are usually in mountains. Glacial headwaters are made by melting glaciers.
The source is where a river begins, and the mouth is where it joins the sea. The source of a river generally discharges water with less force leading to the formation of Interlocking spurs.
The river mouth is the opposite of a river source. The mouth is where the river ends as it meets the ocean, and may have a river delta.
Picture Credit : Google