The traditional method of cupping involving little glass globes that look like the mini fish bowls pet shops keep bettas in. The practitioner puts a small amount of something flammable (such as rubbing alcohol or herbs) inside the cup and lights it on fire. That depletes the oxygen inside the cup.
Then the practitioner turns the cup upside down and places it on your skin. The air inside the cup then cools down, which creates a vacuum. The vacuum causes your skin to dome up inside the cup, which makes the blood vessels expand.
That’s what leaves the signature round suction marks that make it look kind of like you’ve been attacked by an octopus.
Of course, glass and flame aren’t the safest materials to work with.
Because of that, some practitioners have left the globes and flammable materials behind in favor of plastic cups that attach to a pump. They simply put the cup on your skin and squeeze the pump a few times to get the suction going. The effect is the same, only without the risk of burns.
TCM teaches that cupping opens up the pores, stimulates blood flow, and balances your qi (pronounced “chee”), which is the flow of energy through your body.
It’s often combined with acupuncture.