  Over the past decade it has become evident that intentional disinformation in
the political context -- so-called fake news -- is a danger to democracy.
However, until now there has been no clear understanding of how to define fake
news, much less how to model it. This paper addresses both of these issues. A
definition of fake news is given, and two approaches for the modelling of fake
news and its impact in elections and referendums are introduced. The first
approach, based on the idea of a representative voter, is shown to be suitable
for obtaining a qualitative understanding of phenomena associated with fake
news at a macroscopic level. The second approach, based on the idea of an
election microstructure, describes the collective behaviour of the electorate
by modelling the preferences of individual voters. It is shown through a
simulation study that the mere knowledge that fake news may be in circulation
goes a long way towards mitigating the impact of fake news.
