A Salem number is a real algebraic integer, greater than 1, with the proper
ty that all of its conjugates lie on or within the unit circle, and at leas
t one conjugate lies on the unit circle. In this paper we survey some of th
e recent appearances of Salem numbers in parts of geometry and arithmetic,
and discuss the possible implications for the 'minimization problem'. This
is an old question in number theory which asks whether the set of Salem num
bers is bounded away from 1.