WTF is a mirrorless camera?

Digital cameras today tend to fall under one of two categories: SLR or mirrorless. What’s the difference? Why does it matter? To find out, let’s take a quick trip through the history of the medium. It turns out that many of the changes to how cameras work have been attempts to solve a simple problem: how do you show what’s in front of the lens to both the user and whatever’s recording that image?