There are three main stages of a river. Under each stage as some of the most popular characteristics found at each stage.

Youthful stage / upper stage / mountain stage
Steep gradient
Pot holes common
V shaped valley
Fast current
Rapids
Waterfalls

Mature stage / middle stage / valley stage
Less steep than youthful stage
U shaped valley
Slower current
Some meanders

Senile stage / lower stage / plain stage
Shallow gradient
Flat flood plain
Slow current
Meanders
Ox bow lakes
Levees
Deltas