  Nature hosts a wealth of materials showcasing intricate structures
intertwining order, disorder, and hierarchy, delivering resilient
multifunctionality surpassing perfect crystals or simplistic disordered
materials. The engineering of such materials through nanoparticle assembly
represents a burgeoning field, poised with potential to yield sustainable
material systems rivaling or exceeding biological functionalities. This review
delineates the fundamental concept of complexity in the context of nanoscale
materials. It examines methodologies for characterizing complexity and
functionality, explores pragmatic approaches to create complex nanomaterials,
and offers a perspective on their potential applications, guiding the
trajectory of future research endeavors.
