A place 
of a number field 
is an isomorphism class of
field maps 
onto a dense subfield of a nondiscrete locally compact field 
.
In the function field case, let 
be a function field of algebraic functions of one variable
over a field 
. Then by a place in 
, we mean a subset 
of 
which is the ideal of nonunits of some valuation
ring 
over 
.
