Namespace

From Perl Wiki

A Namespace is positioned just above and at the top of a document or other file that contains the title or Name of the Object. Its purpose is to interface something like a page, image, script, variable, &..., song with its environment.

[edit] Programming

A Namespace can also be thought of as a handle in the case of objects or filehandle in the context of perl to be grabbed by a script or handler.

&... is a shorthand representation for a namespace object. See also Wikipedia:use case.