An artist book can be difficult to describe, and there is no one definition that is agreed upon by those of us who create in this field.
What is settled fact is that the artist creates every aspect of the work; structure, binding, and content, and each of these elements can play an equal role in communicating the intent of the artist. An artist book can incorporate traditional and non-traditional materials and media. It may look like a traditional book or may look nothing like it.
But the defining element of an artist book to me is that it reveals rather than presents.