The GW method and the Bethe-Salpeter equation (BSE) have exhibited excellent performance in computing charged and neutral electronic excitations in materials of various dimensions in the past decades. Extensive benchmark studies have demonstrated that their precision can reach the level of high-level ab initio wave function approaches with a much lower computational cost. GW and BSE outperform the density functional theory because of both the more accurate electronic structures in GW and the capability to treat local, charge-transfer, and Rydberg excitations on the same footing in BSE. Presently, they are the only available first-principles approaches that can study electronic excitations at the surface and in the interior of periodic systems and at the interface between periodic systems with reliable accuracy. In this Perspective, a brief overview of GW and BSE and their applications in complex chemical systems is provided, with the goal of boosting their broader utilization in chemistry.