  In nonrelatistic quantum mechanics, Born's principle of localistion is as
follows: For a single particle, if a wave function $\psi_K$ vanishes outside a
spatial region $K$, it is said to be localised in $K$. In particular if a
spatial region $K'$ is disjoint from $K$, a wave function $\psi_{K'}$ localised
in $K'$ is orthogonal to $\psi_K$.
  Such a principle of localisation does not exist compatibly with relativity
and causality in quantum field theory (Newton and Wigner) or interacting point
particles (Currie,Jordan and Sudarshan).It is replaced by symplectic
localisation of observables as shown by Brunetti, Guido and Longo, Schroer and
others. This localisation gives a simple derivation of the spin-statistics
theorem and the Unruh effect, and shows how to construct quantum fields for
anyons and for massless particles with `continuous' spin.
  This review outlines the basic principles underlying symplectic localisation
and shows or mentions its deep implications. In particular, it has the
potential to affect relativistic quantum information theory and black hole
physics.
