Polycrystal

Polycrystals are materials made up of a lot of crystals all stuck together. Imagine that you took a bunch of tiny cubes and taped them together into one big block - this big block would be a polycrystal! Each of the tiny cubes would be made of the same material, and each cube would be an individual crystal. So, when you look at the big block from the outside, it’s a single solid object, but if you were to look at it under a microscope, you would see all of the individual crystals, like tiny cubes, making up the material. Polycrystals are really important because they are used in things like electronics and cars, and they give these things special properties like strength and durability.