Boxes and cartons are small, confined spaces that provide shelter for cats. Even a rectangle just stuck to the floor seems to magically attract them.
A cozy environment releases endorphins in the cat's brain, i.e. triggers feelings of happiness. That's why it can also help to provide a box for a cat to get used to in a new environment. You can find even more exciting animal topics in the free partner newsletter from Landtiere.de, which you can subscribe to right here.