  In the last years the number of nominally non-magnetic solids showing
magnetic order induced by some kind of defects has increased continuously. From
the single element material graphite to several covalently bonded non-magnetic
compounds, the influence of defects like vacancies and/or non-magnetic ad-atoms
on triggering magnetic order has attracted the interest of experimentalists and
theoreticians. We review and discuss the main theoretical approach as well as
recently obtained experimental evidence based on different experimental methods
that supports the existence of defect-induced magnetism (DIM) in non-magnetic
as well as in magnetic materials.
