Imagine you have two pipes with threads on the outside. These pipes need to be connected together, but if you simply screw them together, there could still be tiny gaps where air or water could leak out. A JIC fitting is like a special puzzle piece that helps lock those two pipes together tightly so that no air or water can escape.
A JIC fitting has two parts: the male side and the female side. The male side has threads on the outside that fit into the threads on one of the pipes. The female side also has threads on the inside that fit onto the other pipe. But instead of stopping there, the fitting also has a metal sleeve around the outside that gets pressed down onto the pipes as you screw the fitting together. This squeezing action creates a tight seal and prevents any air or water from getting through.
So when you need to attach two pipes together and create a strong, leak-proof connection, a JIC fitting is like the superhero that comes in to save the day!