Neutron inelastic scattering is a process involved in many applications as nuclear energy or security and safeguard but also for background studies supporting more fundamental research area. In the fast energy range, it is one of the major nucleon-nucleus interactions and its cross section constantly increases above the threshold energy of the first excited state up to a few MeV. During these last decades, despite significant advances in modeling and experimental efforts, cross section calculations still pose a major challenge to nuclear theory and evaluated inelastic cross section are still not at the level of the required accuracy by applications. This contribution is an occasion to present the status of the current knowledge of the neutron inelastic scattering process and to mention how it impacts the field of nuclear energy applications. A description of the different experimental techniques is presented, highlighting some recent advances. Finally, challenges that still need to be met in order to provide accurate neutron inelastic cross sections, as well as current research tracks, will be discussed.