Transpositions are delightful for some composers but a complete nightmare for musicians. Horn players are the kings of transpositions, but why?

This video explains transposition origin, presents all the horn transpositions, and different ways to transpose.

In order to understand it some music theory knowledge about key signatures and music interval is required. If you are a horn beginner, I recommend you to watch the following view instead:
Note names around the world and transposition for horn beginners


You can also practice this 2 transposition games in my website: