The answer can get extremely extensive, but the short answer is a "THING" only exists relative to what is not that thing. If you have a huge wall with only one thing on the wall that is not the wall (maybe a painting or a coat) the thing only exists because of the wall. A thing (anything) only exists because of what is "NOT" that thing. If you had a pure white wall and you took a black magic marker and made a black spot on the otherwise plain white wall, the black spot only exists because of what is not the black spot......the white wall. If you put a white spot on a white wall the spot does NOT exist.
Things exist in relation to what is NOT that thing. Now, Good only exists because not good exists. War only exists because not war exists. Police only exist because criminals exist. You (who is reading this) only exist because something not you exists
You can only identify and point to a thing because of its background of not that thing. If I say see over there, across the valley next to that big tree, do you see that wolf or deer. The tree and wolf (actually the valley) only exist because not that thing exists. If you are laying on a bed, face down and the sheet is white you don't actually/truly know it is white. You need NOT-white to see white.
You only experience pain because you have experience NOT pain. It can't get more in depth, but this is good for now.
If you "crave" a specific thing in your life, as some point (when you are immersed in that thing) the craving stops because you can't grasp the thing you craved, all that exists is what you did crave, but can no longer crave it.
This is the essence of the movie "Shadowlands" (with Debra Winger) She is dying with cancer, she explains the experience of loss/pain/suffering can only exist because of joy/pleasure/ecstasy. You must embrace one to have the other.