Papier-mâché binding is a way to hold together the pages in a book or journal using a mixture of paper and glue.
Imagine you have lots of papers, like the ones you draw on with crayons or markers. If you wanted to make a book out of them, you would need to somehow keep them all together.
One way to do this is by making a cover for the book with a special kind of papier-mâché glue. Papier-mâché is just a fancy way of saying a mix of paper and glue.
So, first you would make a cover for your book by cutting out cardboard or thin wood to the size you want your book to be. Then, you would use the papier-mâché glue to cover the cover!
You might use thin pieces of paper, like tissue paper or newspaper, and layer them on top of each other on the cover until it is covered all over with the papier-mâché mixture.
Once the cover is dry, you would use it to hold all of your pages together by glueing them to the spine, the part of the cover that sticks out and holds the pages together.
And, voila! You have a book that you made yourself using papier-mâché binding.