Questions about Rivers

This post is prompted by a discussion that I read about rivers on a fantasy map. Even though a fantasy map is attached to a fantasy story . . . where all things are created by magical creatures without regard to the laws of physics . . . some people look for scientific principles to hold true. That being said, here is a geography lesson:

When you look at a river you will notice a couple of things.

1. Rivers flow downhill
2. Rivers merge together on their journey to larger bodies of water

Keep those two facts in your head and your rivers will be more realistic and flow naturally across your map.

If you would like a more in depth exploration of the topic, I suggest reading ProFantasy's article. The article is highly informative and explores more of the science and geography of rivers.

Additional Reading:
A Few Notes on Maps: Rivers
River and Lake Formation