  The basin entropy is a simple idea that aims to measure the the final state
unpredictability of multistable systems. Since 2016, the basin entropy has been
widely used in different contexts of physics, from cold atoms to galactic
dynamics. Furthermore, it has provided a natural framework to study basins of
attraction in nonlinear dynamics and new criteria for the detection of fractal
boundaries. In this article, we describe the concept as well as fundamental
applications. In addition, we provide our perspective on the future challenges
of applying the basin entropy idea to understanding complex systems.
