Introduction to Umami

(I know, I had no idea what Umami was either!)

Watching my physiology class online, and the teacher was explaining the different categories of taste. (or something like that.)
To take this course, I'm supposed to have "a basic knowledge in high school physiology."
Well, I'm a freshman in high school. With no basic knowledge. But I understand most of it, and the class is very interesting!  :)
Anyway, she explained sweet, sour, salty, bitter, and then, umami. (pronounced you-ma-me)
I blankly thought "What is that?!"
Apparently, umami is what makes "meat taste like meat." And she said it is also what makes mushrooms taste like meat.
mushrooms?? 
Ok, I don't like mushrooms in the first place, but I definitely don't think they taste like meat.
Or perhaps I've had too much venison in my life, and mushrooms taste like other kinds of meat besides venison..??