  The advent and intensive use of new detector technologies as well as
radioactive ion beam facilities have opened up possibilities to investigate
alpha, proton and cluster decays of highly unstable nuclei. This article
provides a review of the current status of our understanding of clustering and
the corresponding radioactive particle decay process in atomic nuclei. We put
alpha decay in the context of charged-particle emissions which also include
one- and two-proton emissions as well as heavy cluster decay. The experimental
as well as the theoretical advances achieved recently in these fields are
presented. Emphasis is given to the recent discoveries of charged-particle
decays from proton-rich nuclei around the proton drip line. Those decay
measurements have shown to provide an important probe for studying the
structure of the nuclei involved. Developments on the theoretical side in
nuclear many-body theories and supercomputing facilities have also made
substantial progress, enabling one to study the nuclear clusterization and
decays within a microscopic and consistent framework. We report on properties
induced by the nuclear interaction acting in the nuclear medium, like the
pairing interaction, which have been uncovered by studying the microscopic
structure of clusters. The competition between cluster formations as compared
to the corresponding alpha-particle formation are included. In the review we
also describe the search for super-heavy nuclei connected by chains of alpha
and other radioactive particle decays.
