Halo and skin nuclei

The changes in nuclear structure far from the stability line are reviewed for light nuclei. The basic concepts of neutron and proton skins and neutron halos are presented with several experimental data. Signatures of new mode of collective excitation as consequences of such exotic structures are also shown. These changes of structure point to the need for the detailed study of single-particle orbitals for unstable nuclei. Such recent studies, in particular, the spectroscopic information of halo states, are reviewed. Changes of neutron orbital ordering away from the stability line are observed from such studies. Its most profound implication has emerged in the change of magic numbers. An over view of magic number variation is presented.