In the first section of the chapter we introduce the elastic loading Love numbers (LLNs) for a 1-D spherically symmetric planetary model. Then, we define the elastic Green’s functions for the incremental gravitational potential and for vertical and horizontal components of the displacement field. Lastly, a fully worked example is presented, in which the elastic Green’s functions are evaluated for a widely employed SNREI Earth model (REF6371), making use of well established semi-analytical methods. The viscoelastic Love numbers and Green’s functions are succinctly dealt with in the second section, leaving a detailed formal derivation to the appendices of the book. The multi-exponential viscoelastic LNs are constructed by a generalisation of their elastic counterparts, building upon the vast existing literature. Loading and tidal Love numbers are presented both in the time and in the Laplace-transformed domain as a function of the complex frequency s, with explicit expressions for tidal Love numbers being obtained for the case of a periodic forcing. The problem of the computation of Love numbers is addressed in the third section. The analytical solution existing for the so-called Kelvin homogeneous Earth model is presented first, both in terms of LLNs and TLNs. Then, the Darwin solution and the Boussinesq flat-Earth solution are briefly discussed. In the final part, a numerical solution for the LLNs, based upon the open source code TABOO, is presented for a 5-layer viscoelastic model with Maxwell rheology, also describing the spectrum of relaxation for this model.