Splices are critical points in the optical fibre network, because they strongly affect the quality of the links, as well as their lifetime. In fact the splice should ensure high quality and stability of performance with time. High quality in splicing is usually defined as low splice loss and tensile strength near that of the fibre proof-test level. Splices should be stable over the design life of the optical fibre link under its expected environmental conditions. At present two technologies, fusion and mechanical can be used for splicing glass optical fibres and the choice between them depends upon the expected functional performance and considerations of installation and maintenance. These splices are designed to provide permanent connections. The following elements are modified for this revision: Maximum attenuation of fibre splices depending the alignment method (active core, active cladding and passive V-groove alignment); Maximum attenuation for mechanical splices; Validation of splicing procedure is added with average and maximum attenuation (97% of the splices) of fibre splices; The appendix with Japanese experience is removed; An Appendix II which shows the increase in attenuation when splicing different types of optical fibres by taking into account the mode field diameter mismatch, the core-cladding concentricity and the cladding diameter; An Appendix III which explains the fibre imaging process in fusion splicing machines.