Adsorption energies are crucial in determining the performance and stability of heterogeneous catalysts. Knowing what electronic properties control adsorption is therefore important for the rational design of catalysts. These electronic properties can also be used to predict adsorption energies, thereby reducing the time needed for catalyst screening. Here, we discuss the electronic factors responsible for adsorption on metal surfaces (including alloys) and single-atom catalysts, based on past work. Single descriptors like the d-band centre can be powerful in predicting and describing adsorption trends but are usually not accurate over a broad range of materials. Other properties like sp band properties, the coupling matrix element, the d-band shape, and ionic terms (eg, reduction potential and electronegativity) significantly influence adsorption trends on metals and alloys, allowing for higher accuracy. For single atom catalysts, the metal atoms’ electron donating and electron accepting properties also play a major role in determining the adsorption energy.