These proceedings cover the possible manifestations of electron-phonon interactions in understanding high Tc superconductivity. The results of measurements of different experimental methods have been analysed, and the role played by electrons in superconductivity, taking into account the van Hove singularity, has also been discussed. The pairing of electrons by other bosonic excitations, as well as the effects of strong local electron-lattice interactions are reviewed. Another important point is the ab initio calculations discussed by several authors that remark the importance of electron-phonon effects for high Tc superconductivity.