Publisher is an expensive add-on. Be sure that you really need it.
An optional addition to QlikView Server is the Publisher extension, which among other things, allows for the distribution of multiple versions of a document based on a set of data reduction rules. It also allows for QlikView reports to be e-mailed directly to users, again based on a set of data reduction rules.
One of the most useful features of Publisher is the ability to have multiple task triggers for a document reload. This allows for the construction of sophisticated triggers and job cascades. Without Publisher, a document can only have a single task trigger, restricting the options for your reload schedule.