Among all sectors of peptide science, membrane-active peptidology is probably the most promising and fast growing. Membrane-active peptides are a challenge for their involvement in highly heterogeneous systems, the biological membranes. Surface chemistry at the lipid water interface and molecular events in a confined medium such as the lipid bilayer (not exactly 2D, not exactly 3D) are quite appealing, almost irresistible mainly to physical chemists and physical biochemists, whether to study structural aspects of peptide conformation and supra-molecular organization of peptides and/or lipids, or the thermodynamics and kinetics associated to the molecular dynamics of microheterogenous systems. The evolution of biophysical techniques with constant improvement in time and space resolution enables increasingly detailed insights.