What's a Euphonium?

I play the euphonium. I love it, except for one little fact.. no one (except people in band) knows what the heck a euphonium is.  So, for those of you who fall under this category, you've come to the right place! (if you don't go ahead and read anyway!)

Enjoy this picture of a random guy playing a euphonium.

Why did I pick the euphonium?.... I really don't know. It just sounded fun at the time. But my opinion is that it's one of the best instruments ever, just sayin. It's right up there with the mouth harp and the conch shell. I mean, the word itself means sweet-sounding and soothing (well, that's what euphonious means, but close enough right?) But anyway, I get sick of everyone asking what I play, answering, then seeing they're very confused facial expression and knowing I have to try to explain.  I should just always have a bunch of pictures of it with me. I am pretty lazy.
Well, that's my instrument :) spread the word and maybe my job will be a little easier.
Go euphonium players of the world!