Okay kiddo, imagine you have a bunch of building blocks that you can stack on top of each other to make a tower. Each block represents an atom that is part of a solid. When you stack a lot of these atoms together, they form something called a crystal lattice, which is kind of like a tower of building blocks.
Now, the superstructure is like the pattern that these blocks form when you stack them up in a certain way. Some atoms might be bigger or smaller than others, or they might be arranged in a certain pattern. This pattern can create a larger repeating pattern in the crystal, like the repeating pattern on a wallpaper.
Scientists study superstructures in condensed matter because they can tell us a lot about the properties of the material. For example, a superstructure might make a material more magnetic or give it special electrical properties. By studying the superstructure, scientists can understand how these properties work and maybe even design new materials with these properties.
So, superstructure is like the pretty pattern that forms when you stack a bunch of atoms together like a tower of building blocks, and studying this pattern helps scientists understand the cool things a material can do.