In-game screenshot key on PC?

Is there an in-game way to take screenshots? Or do we have to use external tools?

I don't see anything in the options regarding screenshots. Considering games released on the Steam platform typically let Steam handle screenshots, I would have hoped the Battle.net client would as well but I don't think it does. I suppose I could use the Xbox keyboard shortcut to take them (Alt-Win-PrintScreen) but it's technically not part of the game. Did they really not include this?