  We show that the class of large-type Artin groups is invariant under
isomorphism, in stark contrast with the corresponding situation for Coxeter
groups. We obtain this result by providing a purely algebraic characterisation
of large-type Artin groups (i.e. independent of the presentation graph).
  As a corollary, we completely describe the Artin groups isomorphic to a given
large-type Artin group, and characterise those large-type Artin groups that are
rigid.
