Photography like any specialty has its own sets of buzzwords, phrases and rules that just make you ask "What were they Thinking"? I have a few that I swear were created merely to confuse novices and make people in training videos sound like they have something relevant to say.
Lets start, for example, my least favorite phrase regards use of masks in Photoshop. It is very simple and goes something like this,
"white reveals and black conceals".
Or is it "black reveals and white conceals"?
Its a quick little phrase to help you remember whether you want to paint in black or white in the layer mask to hide or expose what is underneath. I don't know where it started, but popular training professionals regurgitate the phrase like its a message from the Heavens to save humanity from their confusion.
When you break it down, there is no context from which to attach meaning. There is no rhyme linking neither black nor white to concealing or revealing. It is a meaningless and senseless phrase and has to be properly memorized to be used in the first place.
To make things worse both are correct (or is it that neither is correct), as it depends whether you think about the mask revealing/concealing the image to which it is attached, or whether it is concealing/revealing the image beneath it. I've seen use of masks described both ways.
That is too much ambiguity! Why not just memorize how to use your photo editor rather than adding on crazy ambiguous phrases? It therefore tops my list as the most useless and annoying phrase one could give to someone learning how to use layer masks in their photo editing software.
Here is a simpler way to think about it... Each layer is like a sheet of paper or transparency projected onto a screen. (much like the ones use when you were in school... assuming you are also old enough where such relics were used). The light is white and is what allows the image to be seen. If you put a black sheet of paper over part of the image, it is not seen. In other words, black blocks the image from being displayed.
Hmmm, "black blocks"? Look at that! They are nearly the same word, and the relation between them makes sense. How much simpler can it be to remember that? But if you want to go further, the "light is white". Not only do the words rhyme, but it makes logical sense that the light shines through and allows the image to be seen. And in most cases the light is going to be a white light. Additionally, one can easily recreate the relation between the two without having to memorize random associations.
You might be asking yourself, how do I keep track of whether "black blocks" the current image or the image(s) beneath? Well, the mask is attached to the image which it affects. Simple as that.