This chapter is devoted to the nonlinear modal analysis of a nonsmooth academic vibro-impact oscillator. The aim is to introduce the classical ingredients of nonlinear modal analysis in a quasi-exact fashion. Periodic solutions, backbone curves in Frequency-Energy Plots, invariant manifolds, (grazing) bifurcation mechanisms, internal resonances, model-order reduction considerations and superabundance of nonlinear modes naturally emerge when solving the governing equations. Spectral stability analysis of (some) periodic orbits and time-domain solutions in their vicinity are also provided.