We discuss the challenges of using the GW and BSE methods to analyze complex molecular systems, which are made up of molecules with enough structural disorder to localize electronic states. Due to the high computational cost and O(N 4 ) scaling of these methods, it is impractical to apply them to large systems such as solid-liquid interfaces, molecules in solution, complex alloys, and nanostructures. As a solution, embedding strategies are considered as they offer a good balance between accuracy and computational cost for modeling large molecular systems. In these strategies, a specific part of the system (I) is treated with higher accuracy (the subsystem of interest), while the rest (II) is addressed with a lower accuracy method (the embedding region). In this review, the high-accuracy Many-Body Green's function method (GW -BSE) is discussed as the preferred method for studying electronically excited states, and its coupling with different methods used in the embedding region is explored.