Definition: A frame $F$ is a suplattice such that for any $x_{i}, y\in F$ (for $i\in I$, $I$ a set), we have $$y\wedge\left(\bigvee_{i\in I}x_i\right)=\bigvee_{i\in I}(y\wedge x_i).$$
Why are frames called "frames"?
Is there some mental picture of them I'm missing that resembles a frame of some sort? I don't understand. I've looked in all the standard places (I know of) . . .
I ask because I'm hoping it'll give me a better idea of what they are.