- A river watershed is all of the area that has water draining into a river. Any streams or creeks that flow into a river, and the areas of rain runoff that feed these streams, are part of the watershed. It's easy to remember if you think of a watershed "shedding water" into the river.
- Headwaters are the beginnings of rivers. They might be streams so small and narrow that you could jump across, or places where water bubbles out of the ground from underground springs. River headwaters usually originate in high places.
- An estuary (ES-chuh-wer-e) is the outlet where a river meets the sea. It's the end of the river, and it's lowest point. Estuaries are also called bays, lagoons, sounds or inlets. Water in estuaries is often a little salty because sea water is mixing with the fresh water from the river.
- A tributary is a stream or river that joins with a larger stream or river.
- A delta is land that builds up when eroded clay and sand settles at the mouth of a river.
- A channel is the bottom and either side of a river or stream.